数据库有关的中英文翻译
数据库(中英文翻译)
原文：Planning the DatabaseIt is important to plan how the logical storage structure of the database will affect system performance and various database management operations. For example, before creating any tablespaces for your database, you should know how many data files will make up the tablespace,what type of information will be stored in each tablespace, and on which disk drives the datafiles will be physically stored. When planning the overall logical storage of the database structure, take into account the effects that this structure will have when the database is actually created and running.You may have database objects that have special storage requirements dueto type or size.In distributed database environments, this planning stage is extremely important. The physical location of frequently accessed data dramatically affects application performance.During the planning stage, develop a backup strategy for the database. You can alter the logical storage structure or design of the database to improve backup efficiency. Backup strategies are introduced in a later lesson.These are the types of questions and considerations, which you will encounter as a DBA, and this course (in its entirety) is designed to help you answer them.Databases: ExamplesDifferent types of databases have their own specific instance and storage requirements. YourOracle database software includes templates for the creation of these different types of databases.Characteristics of these examples are the following:• Data Warehouse: Store data for long periods and retrieve them in read operations.• Transaction Processing: Accommodate many, but usually small, transactions.• General Purpose: Work with transactions and store them for a medium length of time.Database Configuration Assistant (DBCA)You can use the Database Configuration Assistant (DBCA) to create, change the configuration of, or delete a database. You can also create a database from a list of predefined templates or use an existing database as a sample to create a new database or template. This is sometimes referred to as “database cloning.”You can invoke the DBCA by performing the following steps:1. Log on to your computer as a member of the administrative group that is authorized to install the Oracle software.2. If required, set environment variables.3. Enter dbca to invoke the DBCA.4. Click Next to continue.DBCA offers you a choice of assisting with several operations, for example, creating a database.Using the DBCA to Create a DatabaseYou can use the DBCA to create a database as follows:1. Select Create a Database on the DBCA Operations page to invoke a wizard that enables you to configure and create a database.The wizard prompts you to provide configuration information as outlined in the steps that follow. On most pages, the wizard provides a default setting that you can accept.2. Select the type of database template to be used in creating the database. There aretemplates for Data Warehouse, General Purpose, and Transaction Processing databases that copy a preconfigured database, including data files. These data files include control files,redo log files, and data files for various included tablespaces.Click Show Details to see the configuration for each type of database.For more complex environments, you may want to select the Custom Database option. Password ManagementAfter the DBCA finishes, note the following information for future reference:• Location of installation log files (see A)• Global database name (see B)• System identifier (SID) (see B)• Server parameter file name and location (see B)• Enterpr ise Manager URL (see C)Click Password Management to unlock database accounts that you plan to use.Provide apassword when you unlock an account.Creating a Database Design TemplateA template is a predefined database definition that you use as a starting point for a new database.If you do not create a template as part of the database creation process, you can do it anytime by invoking the DBCA. You have three ways to create a template: • From an existing template• From an existing database (structure only)• From an existing database (structure as well as data)The DBCA guides you through the steps to create a database design template.Using the DBCA to Delete a DatabaseTo delete (or configure) a database in UNIX or Linux, you must set ORACLE_SID in the shell from which DBCA is launched. Start the DBCA by entering dbca in a terminal window, and click Next on the Welcome page. To delete the database, perform the following steps:1. On the Operations page, select Delete a Database, and click Next.2. Select the database that you want to delete (in class, hist), and click Finish.3. Click Yes to confirm your deletion.Using the DBCA to Delete a Database (continued)Dropping a database involves removing its data files, redo log files, control files, and initialization parameter files. The DROP DATABASE statement deletes all control files and all other database files listed in the control file. To use the DROP DATABASE statement successfully,all the following conditions must apply:The database must be mounted and closed.The database must be mounted exclusively—not in shared mode.The database must be mounted as RESTRICTED.An example of this statement is:DROP DATABASE;The DROP DATABASE statement has no effect on archived log files nor does it have any effect on copies or backups of the database. It is best to use Recovery Manager (RMAN) to delete such files. If the database is on raw disks, then the actual raw disk special files are not deleted.Management FrameworkThere are three major components of the Oracle database management framework: • The database instance that is being managed• A listener that allows connections to the database• The management interface. This may be either a management agent running onthe database server (which connects it to Oracle Enterprise Manager Grid Control) or the stand-alone Oracle Enterprise Manager Database Control. This is also referred to as Database Console.Each of these components must be explicitly started before you can use the services of the component and must be shut down cleanly when shutting down the server hosting the Oracle database.The first component to be started is the management interface. After this is activated, the management interface can be used to start the other components. Starting and Stopping Database ControlOracle provides a stand-alone management console called Database Control for databases that are not connected to the Grid Control framework. Each database that is managed with Database Control has a separate Database Control installation, and from any one Database Control, you can manage only one database. Before using Database Control, ensure that a dbconsole process is started.To start the dbconsole process, use the following command:emctl start dbconsole To stop the dbconsole process, use the following command:emctl stop dbconsole To view the status of the dbconsole process, use the following command:emctl status dbconsole.Note: You may need to navigate to your $ORACLE_HOME/bin directory if this directory is not in your operating system (OS) path.Database Control uses a server-side agent process. This agent process automatically starts and stops when the dbconsole process is started or stopped.译文：规划数据库规划如何对数据库的逻辑存储结构将影响系统的性能和各种数据库管理操作是非常重要的。
数据库中英文对照外文翻译文献
中英文对照外文翻译Database Management SystemsA database (sometimes spelled data base) is also called an electronic database , referring to any collection of data, or information, that is specially organized for rapid search and retrieval by a computer. Databases are structured to facilitate the storage, retrieval , modification, and deletion of data in conjunction with various data-processing operations .Databases can be stored on magnetic disk or tape, optical disk, or some other secondary storage device.A database consists of a file or a set of files. The information in these files may be broken down into records, each of which consists of one or more fields. Fields are the basic units of data storage , and each field typically contains information pertaining to one aspect or attribute of the entity described by the database . Using keywords and various sorting commands, users can rapidly search , rearrange, group, and select the fields in many records to retrieve or create reports on particular aggregate of data.Complex data relationships and linkages may be found in all but the simplest databases .The system software package that handles the difficult tasks associated with creating ,accessing, and maintaining database records is called a database management system(DBMS).The programs in a DBMS package establish an interface between the database itself and the users of the database.. (These users may be applications programmers, managers and others with information needs, and various OS programs.)A DBMS can organize, process, and present selected data elements form the database. This capability enables decision makers to search, probe, and query database contents in order to extract answers to nonrecurring and unplanned questions that aren’t available in regular reports. These questions might initially be vague and/or poorly defined ,but people can “browse” through the database until they have the needed information. In short, the DBMS will “manage” the stored data items and assemble the needed items from the common database in response to the queries of those who aren’t programmers.A database management system (DBMS) is composed of three major parts:(1)a storage subsystemthat stores and retrieves data in files;(2) a modeling and manipulation subsystem that provides the means with which to organize the data and to add , delete, maintain, and update the data;(3)and an interface between the DBMS and its users. Several major trends are emerging that enhance the value and usefulness of database management systems;Managers: who require more up-to-data information to make effective decisionCustomers: who demand increasingly sophisticated information services and more current information about the status of their orders, invoices, and accounts.Users: who find that they can develop custom applications with database systems in a fraction of the time it takes to use traditional programming languages.Organizations : that discover information has a strategic value; they utilize their database systems to gain an edge over their competitors.The Database ModelA data model describes a way to structure and manipulate the data in a database. The structural part of the model specifies how data should be represented(such as tree, tables, and so on ).The manipulative part of the model specifies the operation with which to add, delete, display, maintain, print, search, select, sort and update the data.Hierarchical ModelThe first database management systems used a hierarchical model-that is-they arranged records into a tree structure. Some records are root records and all others have unique parent records. The structure of the tree is designed to reflect the order in which the data will be used that is ,the record at the root of a tree will be accessed first, then records one level below the root ,and so on.The hierarchical model was developed because hierarchical relationships are commonly found in business applications. As you have known, an organization char often describes a hierarchical relationship: top management is at the highest level, middle management at lower levels, and operational employees at the lowest levels. Note that within a strict hierarchy, each level of management may have many employees or levels of employees beneath it, but each employee has only one manager. Hierarchical data are characterized by this one-to-many relationship among data.In the hierarchical approach, each relationship must be explicitly defined when the database is created. Each record in a hierarchical database can contain only one key field and only one relationship is allowed between any two fields. This can create a problem because data do not always conform to such a strict hierarchy.Relational ModelA major breakthrough in database research occurred in 1970 when E. F. Codd proposed a fundamentally different approach to database management called relational model ,which uses a table asits data structure.The relational database is the most widely used database structure. Data is organized into related tables. Each table is made up of rows called and columns called fields. Each record contains fields of data about some specific item. For example, in a table containing information on employees, a record would contain fields of data such as a person’s last name ,first name ,and street address.Structured query language(SQL)is a query language for manipulating data in a relational database .It is nonprocedural or declarative, in which the user need only specify an English-like description that specifies the operation and the described record or combination of records. A query optimizer translates the description into a procedure to perform the database manipulation.Network ModelThe network model creates relationships among data through a linked-list structure in which subordinate records can be linked to more than one parent record. This approach combines records with links, which are called pointers. The pointers are addresses that indicate the location of a record. With the network approach, a subordinate record can be linked to a key record and at the same time itself be a key record linked to other sets of subordinate records. The network mode historically has had a performance advantage over other database models. Today , such performance characteristics are only important in high-volume ,high-speed transaction processing such as automatic teller machine networks or airline reservation system.Both hierarchical and network databases are application specific. If a new application is developed ,maintaining the consistency of databases in different applications can be very difficult. For example, suppose a new pension application is developed .The data are the same, but a new database must be created.Object ModelThe newest approach to database management uses an object model , in which records are represented by entities called objects that can both store data and provide methods or procedures to perform specific tasks.The query language used for the object model is the same object-oriented programming language used to develop the database application .This can create problems because there is no simple , uniform query language such as SQL . The object model is relatively new, and only a few examples of object-oriented database exist. It has attracted attention because developers who choose an object-oriented programming language want a database based on an object-oriented model. Distributed DatabaseSimilarly , a distributed database is one in which different parts of the database reside on physically separated computers . One goal of distributed databases is the access of informationwithout regard to where the data might be stored. Keeping in mind that once the users and their data are separated , the communication and networking concepts come into play .Distributed databases require software that resides partially in the larger computer. This software bridges the gap between personal and large computers and resolves the problems of incompatible data formats. Ideally, it would make the mainframe databases appear to be large libraries of information, with most of the processing accomplished on the personal computer.A drawback to some distributed systems is that they are often based on what is called a mainframe-entire model , in which the larger host computer is seen as the master and the terminal or personal computer is seen as a slave. There are some advantages to this approach . With databases under centralized control , many of the problems of data integrity that we mentioned earlier are solved . But today’s personal computers, departmental computers, and distributed processing require computers and their applications to communicate with each other on a more equal or peer-to-peer basis. In a database, the client/server model provides the framework for distributing databases.One way to take advantage of many connected computers running database applications is to distribute the application into cooperating parts that are independent of one anther. A client is an end user or computer program that requests resources across a network. A server is a computer running software that fulfills those requests across a network . When the resources are data in a database ,the client/server model provides the framework for distributing database.A file serve is software that provides access to files across a network. A dedicated file server is a single computer dedicated to being a file server. This is useful ,for example ,if the files are large and require fast access .In such cases, a minicomputer or mainframe would be used as a file server. A distributed file server spreads the files around on individual computers instead of placing them on one dedicated computer.Advantages of the latter server include the ability to store and retrieve files on other computers and the elimination of duplicate files on each computer. A major disadvantage , however, is that individual read/write requests are being moved across the network and problems can arise when updating files. Suppose a user requests a record from a file and changes it while another user requests the same record and changes it too. The solution to this problems called record locking, which means that the first request makes others requests wait until the first request is satisfied . Other users may be able to read the record, but they will not be able to change it .A database server is software that services requests to a database across a network. For example, suppose a user types in a query for data on his or her personal computer . If the application is designed with the client/server model in mind ,the query language part on the personal computer simple sends the query across the network to the database server and requests to be notified when the data are found.Examples of distributed database systems can be found in the engineering world. Sun’s Network Filing System(NFS),for example, is used in computer-aided engineering applications to distribute data among the hard disks in a network of Sun workstation.Distributing databases is an evolutionary step because it is logical that data should exist at the location where they are being used . Departmental computers within a large corporation ,for example, should have data reside locally , yet those data should be accessible by authorized corporate management when they want to consolidate departmental data . DBMS software will protect the security and integrity of the database , and the distributed database will appear to its users as no different from the non-distributed database .In this information age, the data server has become the heart of a company. This one piece of software controls the rhythm of most organizations and is used to pump information lifeblood through the arteries of the network. Because of the critical nature of this application, the data server is also the one of the most popular targets for hackers. If a hacker owns this application, he can cause the company's "heart" to suffer a fatal arrest.Ironically, although most users are now aware of hackers, they still do not realize how susceptible their database servers are to hack attacks. Thus, this article presents a description of the primary methods of attacking database servers (also known as SQL servers) and shows you how to protect yourself from these attacks.You should note this information is not new. Many technical white papers go into great detail about how to perform SQL attacks, and numerous vulnerabilities have been posted to security lists that describe exactly how certain database applications can be exploited. This article was written for the curious non-SQL experts who do not care to know the details, and as a review to those who do use SQL regularly.What Is a SQL Server?A database application is a program that provides clients with access to data. There are many variations of this type of application, ranging from the expensive enterprise-level Microsoft SQL Server to the free and open source mySQL. Regardless of the flavor, most database server applications have several things in common.First, database applications use the same general programming language known as SQL, or Structured Query Language. This language, also known as a fourth-level language due to its simplistic syntax, is at the core of how a client communicates its requests to the server. Using SQL in its simplest form, a programmer can select, add, update, and delete information in a database. However, SQL can also be used to create and design entire databases, perform various functions on the returned information, and even execute other programs.To illustrate how SQL can be used, the following is an example of a simple standard SQL query and a more powerful SQL query:Simple: "Select * from dbFurniture.tblChair"This returns all information in the table tblChair from the database dbFurniture.Complex: "EXEC master..xp_cmdshell 'dir c:\'"This short SQL command returns to the client the list of files and folders under the c:\ directory of the SQL server. Note that this example uses an extended stored procedure that is exclusive to MS SQL Server.The second function that database server applications share is that they all require some form of authenticated connection between client and host. Although the SQL language is fairly easy to use, at least in its basic form, any client that wants to perform queries must first provide some form of credentials that will authorize the client; the client also must define the format of the request and response.This connection is defined by several attributes, depending on the relative location of the client and what operating systems are in use. We could spend a whole article discussing various technologies such as DSN connections, DSN-less connections, RDO, ADO, and more, but these subjects are outside the scope of this article. If you want to learn more about them, a little Google'ing will provide you with more than enough information. However, the following is a list of the more common items included in a connection request.Database sourceRequest typeDatabaseUser IDPasswordBefore any connection can be made, the client must define what type of database server it is connecting to. This is handled by a software component that provides the client with the instructions needed to create the request in the correct format. In addition to the type of database, the request type can be used to further define how the client's request will be handled by the server. Next comes the database name and finally the authentication information.All the connection information is important, but by far the weakest link is the authentication information—or lack thereof. In a properly managed server, each database has its own users with specifically designated permissions that control what type of activity they can perform. For example, a user account would be set up as read only for applications that need to only access information. Another account should be used for inserts or updates, and maybe even a third account would be used for deletes.This type of account control ensures that any compromised account is limited in functionality. Unfortunately, many database programs are set up with null or easy passwords, which leads to successful hack attacks.译文数据库管理系统介绍数据库（database,有时拼作data base）又称为电子数据库，是专门组织起来的一组数据或信息，其目的是为了便于计算机快速查询及检索。
外文翻译--关于数据库死锁的知识
外文翻译About the database of the knowledge of the deadlock Database itself provides lock management mechanism, but from a hand, database is the client applications "puppet", this is mainly because the client to the server has complete control of the gain of locks ability. The client in enquiries in the request and the way to query processing tend to have direct control, so, if we application design reasonable enough, then appear database is normal phenomenon dead lock.Below are listed some easy to have locked application examples:A, the client cancel inquires no roll back after practice.Most of the application is inquires often happens homework. However, users through the front desk the client application inquires the backend database, sometimes will cancel inquires for any variety of reasons. If the user to open the window after mouth query, because users find reflect crash or slow compelled to cancel the query. But, when the client when cancel inquires, if not add rollback transaction statement, then at this time, because the user has to the server sends the inquiry's request, so, the backend database involved in the table, all have been added L locked. So even if the user cancel after inquires, all in the affairs for the locks within will remain. At this point, if other users need to check on the table or the user to open the window through input inquires to query conditions to improve the system response speed occurs when the jam phenomenon.Second, the client not to get all the results of my query.Usually, the user will be sent to the server after queries, foreground application must be done at once extraction all the results do. If the application did not extract all the results trip, it produces a problem. For as long as the application did not withdraw promptly all the results, the lock may stay at table and block other users. Since the application has been submitted to the server will SQ statements, the application must be extracted all results do. If the application does not follow the principle words (such as because at that time and no oversight configuration), can't fundamentally solve congestion.Three, inquires the execution time too long.Some inquires a relatively long time will cost. As for the query design is not reasonable or query design to watch and record it is, will make inquires the execution time lengthen. If sometimes need to Update on users record or Delete operation, if the line is involved in it, you will get a lot of lock. These locks whether finally upgrade to watch the lock, can block other inquiries.So often, don't take long time running decision support search and online transaction processing inquires the mixed together.When database meet blocked, often need to check the application submitted to the SQL statement itself, and check and connection management, all the results do processing and other relevant application behavior. Usually, the lock for to avoid the conflict in the jam, the author has the following Suggestions.Suggest a: after the completion of the extraction of all query results do.Some applications in order to improve the response speed of the user inquires, will have the option of extraction need record. The "smart" looks very reasonable, but, but will cause more waste. Because inquires not timely and fruit extraction of words, the lock cannot be released. When others inquires the data, will be happening.So, the author suggest in application design, database query for record to the extraction of in time. Through other means, such as adding inquires the conditions, or the way backstage inquires, to improve the efficiency of the inquires. At the same time, in the application level set reasonable cache, and can also be very significantly improved query efficiency.Suggest two: in the transaction execution don't let the user input content.Although in the affairs of the process with sex, can let the user participation, in order to improve the interactivity. But, we don't recommend the database administrator tend to do so. Because if the user in affairs during the exec ution of the input and number, will extend the affairs of the execution time. Although people smarter, but the response speed still don't have a computer so fast. So, during the implementation of the user participation to let the process, will extend the a ffairs of waiting time. So unless there is a special needs, not in the application's execution process, reminds the user input parameters. Some affairs of the executive must parameters, best provide beforehand. If can through the variables in the parameters such as need to go in.Suggest three: make affairs as far as possible the brief.The author thinks that, database administrator should put some problem is simplified. When a need to many SQL statements to complete, might as well take the task decomposition. At the same time, it breaks down into some brief business affairs.If the database a product information table, its record number two million. Now in a management needs, the one-time change one of the one million five hundred thousand record. If through a change affairs, the time is long. If it involves cascade update it, is time the meeting is longer.In view of this situation, we can learn affairs brief words. If the product information, may have a product type field. So in the update data, can we not one-time updates. But through the product category fields to control, to record the iteration points. So every category of update firm consumption of time may be greatly reduces. So although operation, will need more steps. But, can effectively avoid to go to the occurrence of congestion, and improve the performance of the database. Suggest four: child inquires the and list box, had better not use at the same time.Sometimes in the application of design, through the list box can really improve user input speed and accuracy, but, if foreground application does not have buffer mechanism, you often can cause congestion.As in a order management system, may need frequent input sales representatives. In order to user input convenience, sales representative often design into a list box. Every time need to input, foreground application from the background of all sales representative inquires information (if the application is not involved in the cache). On one hand, the son of nature, would be speed query slow; Second, the list box have growth time operation of the inquiry. The two parties face touch together, may causethe application of improving the running time process query. And the other user queries, such as the system administrator need to maintain customer information, and cause congestion.So, in the application design, the child inquires the best less. And the child inquires the list box and use at the same time, more need to ban. If you can't avoid it, should be in application realize caching mechanism. That way, the applications need to sales representative information, will from application cache made, not every time to check the database.At the same time, can be in the list box design "to search" function. When there is a change to the user information, such as the system administrator to join a new sales representatives. In no again before inquires, because of their application is achieved in the cache data, so not just updated content. At this time, users will need to run to inquires the function, let the foreground application from a database query information again. This kind of design, can increase the list box and the son of the execution time inquires, effectively avoid congestion.Suggest five: in the set when cancel inquires back issues.Foreground application is designed, should allow users to a temporary change in idea, cancel the query. Such as user inquires the all product information, may feel response time is long, hard to bear. At this time, they will think of cancel inquires the. In this case, the application design need to design a cancel inquires the button. The user can in the process of inquires click this button cancel inquires at any time. Meanwhile, in the button affair, need to pay attention to join a rollback command. Let the database server can prompt to records or table to unlock.At the same time to the best lock or query timeout mechanism. This is largely because, sometimes also can cost a lot inquires user host to a large number of resources, and cause client crash. At this time, to be able to lock the inquires the or overtime mechanisms, namely in inquires after overtime, database server of related objects for automatic unlock. This is also the database administrator need to program developers negotiation of a problem.In addition, explicit database connection to take control in the concurrent users, is expected to full load next use application to bear ability test, use the link, each inquires to set use inquires and lock exceeds the overtime, these methods can effectively avoid the lock conflict obstruction. When database administrators found that blocking the symptoms, can from these aspect, looking for solutions.From the above analysis can see, SQL Server database lock is a double-edged sword. The security database data consistency at the same time, they will give the database caused some negative effect. How do these negative influence to the least, is our database administrators task. In application design, follow the advice above, can effectively solve the problems for the lock blockages, improve the performance of the database. Visible, to basically solve congestion problem, need database management personnel and program developers work together.中文关于数据库死锁的知识数据库本身提供了锁管理机制,但是从一方面,数据库客户端应用程序的“傀儡”,这主要是由于客户端到服务器的完全控制获得的锁的能力。
retrieval 翻译
retrieval 翻译retrieval的中文翻译是“检索”或“获取”，它用于描述从存储设备或数据库中提取信息的过程。
以下是一些关于retrieval的用法和中英文对照例句：1. The retrieval of data from the database was quick and efficient.数据库中的数据检索非常迅速和高效。
2. Information retrieval systems are widely used in libraries and search engines.信息检索系统广泛应用于图书馆和搜索引擎。
3. The software allows for the retrieval of deleted files.这款软件可以检索已删除的文件。
4. The retrieval process can be automated to save time and effort.检索过程可以自动化，以节省时间和精力。
5. The search engine uses complex algorithms for information retrieval.这个搜索引擎使用复杂的算法进行信息检索。
6. The retrieval of relevant documents is crucial forconducting research.检索相关文献对于进行研究至关重要。
7. The retrieval of historical records helped shed light on the past.检索历史记录有助于揭示过去的情况。
8. The retrieval of personal data must comply with privacy laws.检索个人数据必须遵守隐私法规。
9. The database provides fast and accurate retrieval of customer information.数据库提供快速准确的客户信息检索。
计算机网络中英文互译
计算机网络中英翻译ACK (ACKnowledgement) 确认帧ADSL (Asymmetric Digital Subscriber Line) 非对称数字用户线AN (Access Network ）接入网ANSI (American National Standards Institute) 美国国家标准协会AP (Access Point) 接入点API (Application Programming Interface) 应用编程接口APNIC (Asia Pacific Network Information Center) 亚太网络信息中心ARP （ Address Resolution Protocol ）地址解析协议ARPA (Advanced Research Project Agency)美国国防部远景研究规划局（高级研究计划署）ARQ (Automatic Repeat reQuest) 自动请求重发ATM (Asynchronous Transfer Mode) 异步传递方式ATU (Access Termination Unit) 接入端接单元ATU-C (Access Termination Unit Central Office ）端局接入端接单元ATU-R (Access Termination Unit Remote) 远端接入端接单元AUI (Attachment Unit Interface ）连接接口单元AWT （ Abstract Window Toolkit ）抽象窗口工具箱BECN (Backward Explicit Congestion Notification) 反向显式拥塞通知BER (Basic Encoding Rule) 基本编码规则BGP (Border Gateway Protocol) 边界网关协议BSA (Basic Service Area) 基本服务区BSS (Basic Service Set) 基本服务集BNA 宝来网络体系结构CAC (Connection Admission Control) 连接准许控制CAP (Carrierless Amplitude Phase) 无载波振幅相位调制CATV (Community Antenna TV, CAble TV) 有线电视CBR （ Constant Bit Rate ）恒定比特率CCIR (Consultative Committee，International Radio) 国际无线电咨询委员会CCITT (Consultative Committee, International Telegraph and Telephone)国际电报电话咨询委员会CCP 通信控制处理机CDM (Code Division Multiplexing) 码分复用CDMA (Code Division Multiplex Access) 码分多址CNNIC (Network Information Center of China) 中国互联网络信息中心CRC (Cyclic Redundancy Check) 循环冗余检验CSMA/CD (Carrier Sense Multiple Access ／ Collision Detection)载波监听多点接入/碰撞检测CSU/DSU （ Channel Service Unit/Data Service Unit) 信道服务单元／数据服务单元CTD (Cell Transfer Delay) 信元传送时延DACS (Digital Access and Cross-connect System) 数字交接系统DCA 数据通信体系结构DCE (Data Circuit-terminating Equipment) 数据电路端接设备DE (Discard Eligibility) 丢弃指示DES (Data Encryption Standard) 数据加密标准DHCP (Dynamic Host Configuration Protocol) 动态主机配置协议DLCI (Data Link Connection Identifier) 数据链路连接标识符DMT (Discrete Multi-Tone) 离散多音（调制）DNS (Domain Name System) 域名系统DNA 数据网络系统结构DSL (Digital Subscriber Line) 数字用户线DSLAM (DSL Access Multiplexer) 数字用户线接入复用器DSSS (Direct Sequence Spread Spectrum) 直接序列扩频DTE (Data Terminal Equipment) 数据终端设备DVMRP (Distance Vector Multicast Routing Protocol) 距离向量多播路由选择协议DWDM (Dense WDM) 密集波分复用EGP (External Gateway Protocol) 外部网关协议EIA (Electronic Industries Association ）美国电子工业协会ESP (Encapsulating Security Payload) 封装安全有效载荷ESS 伍 xtended Service Set) 扩展的服务集FCS (Frame Check Sequence) 帧检验序列FDDI (Fiber Distributed Data Interface ）光纤分布式数据接口FDM (Frequency Division Multiplexing) 频分复用FEC (Forwarding Equivalence Class) 转发等价类FEC (Forward Error Correction) 前向纠错FHSS (Frequency Hopping Spread Spectrum) 跳频扩频FIFO （ First In First Out) 先进先出FQ (Fair Queuing) 公平排队FR (Frame Relay) 帧中继FSK (Frequency Shift Keying) 移频键控FTP (File Transfer Protocol ）文件传送协议FTTB (Fiber To The Building) 光纤到大楼FTTC (Fiber To The Curb ）光纤到路边FTTH (Fiber To The Home) 光纤到家FTTD (Fiber To The Desk) 光纤到桌面FTTZ(Fiber To The Zone ）光纤到小区FTTO (Fiber To The Office) 光纤到办公室FTTF (Fiber To The Floor) 光纤到楼层GIF (Graphics Interchange Format) 图形交换格式GII (Global Information Infrastructure) 全球信息基础结构，全球信息基础设施GFC （ Generic Flow Control) 通用流量控制GSM (Group Special Mobile) 群组专用移动通信体制HDLC (High-level Data Link Control) 面向比特的链路控制规程HDSL (High speed DSL) 高速数字用户线HEC (Header Error Control) 首部差错控制HFC (Hybrid Fiber Coax) 光纤同轴混合（网）HTML (HyperText Markup Language) 超文本置标语言HTTP (HyperText Transfer Protocol) 超文本传送协议IAB (Internet Architecture Board) 因特网体系结构委员会IAC （ Interpret As Command ）作为命令解释IAHC (Internet International Ad Hoc Committee ）因特网国际特别委员会ICMP （ Internet Control Message Protocol ）因特网控制报文协议IDEA (International Data Encryption Algorithm) 国际数据加密算法IEEE电气和电子工程师协会IESG (Internet Engineering Steering Group) 因特网工程指导小组IETF (Internet Engineering Task Force) 因特网工程部IFS (Inter Frame Space) 帧间间隔IGMP (Internet Group Management Protocol) 因特网组管理协议IGP (Interior Gateway Protocol) 内部网关协议IM (Instant Messaging) 即时传信IMAP (Internet Message Access Protocol) 因特网报文存取协议IMP （ Interface Message Processor) 接口报文处理机IP (Internet Protocol ）网际协议IR (InfraRed ）红外技术IRTF （ Internet Research Task Force ）因特网研究部ISDN (Integrated Services Digital Network) 综合业务数字网ISO （ International Organization for Standardization ）国际标准化组织ISOC (Internet Society) 因特网协会ISP （ Internet Service Provider) 因特网服务提供者ITU （ International Telecommunication Union ）国际电信联盟ITU-T （ ITU Telecommunication Standardization Sector) 国际电信联盟电信标准化部门JPEG (Joint Photographic Expert Group) 联合图像专家组标准KDC (Key Distribution Center) 密钥分配中心LAN (Local Area Network ）局域网LANE (LAN Emulation ）局域网仿真LAPB (Link Access Procedure Balanced) 链路接入规程（平衡型）LCP (Link Control Protocol) 链路控制协议LDP (Label Distribution Protocol) 标记分配协议LLC (Logical Link Control) 逻辑链路控制LSP (Label Switched Path) 标记交换路径LSR (Label Switching Router) 标记交换路由器MAC (Medium Access Control) 媒体接入控制MAN (Metropolitan Area Network) 城域网MAU (Medium Attachment Unit) 媒体连接单元MBONE (Multicast Backbone On the InterNEt ）多播主干网MBS (Maximum Burst Size ）最大突发长度MCR (Minimum Cell Rate ）最小信元速率 MCU (Multipoint Control Unit)多点控制单元MD (Message Digest) 报文摘要MDI (Medium Dependent Interface ）媒体相关接口MIB (Management Information Base) 管理信息库MIME (Multipurpose Internet Mail Extensions) 通用因特网邮件扩充modem 调制解调器MOTIF (Message Oriented Text Interchange System) 面向报文的电文交换系统MPEG (Motion Picture Experts Group) 活动图像专家组标准MPOA (MultiProtocol Over ATM) 多协议在 ATM 上运行MPLS (MultiProtocol Label Switching) 多协议标记交换MRU (Maximum Receive Unit) 最大接收单元MSS (Maximum Segment Size) 最长报文段MTU (Maximum Transfer Unit) 最大传送单元NAK (Negative AcKnowlegement) 否认帧NAP （ Network Access Point) 网络接入点N.ISDN (Narrowband-ISDN) 窄带综合业务数字网NAT (Network Address Translation ）网络地址转换NAV (Network Al location Vector) 网络分配向量NCP (Network Control Protocol) 网络控制协议NFS (Network File System) 网络文件系统NGI 下一代因特网计划NIA 网络适配器NIC (Network Interface Card) 网络接口卡、网卡NII (National Information Infrastructure) 国家信息基础结构，国家信息基础设施NLRI (Network Layer Reachability Information) 网络层可达性信息NNI (Network-Node Interface) 网络结点接口NSF (National Science Foundation) （美国）国家科学基金会NVT (Network Virtual Terminal ）网络虚拟终端ODBC （Open Database Connection）开放数据库互连OSF （Open Software Fundation ）开放软件基金会OSI （Open System Interconnection ）开放系统互联PBX （Private Branch eXchange ）用户交换机PCM (Pulse Code Modulation ) 脉冲编码调制PCN (Personal Communications Network ) 个人通信网络PCR （Peak Cell Rate ）峰值信元速率PCS 个人通信服务 Personal Communications ServicePDH 准同步数字系列PDA 个人数字助理 Personal Digital AssistantPDN 公用数据网 Public Data NetworkPDU 协议数据单元 Protocol Data UnitPER 分组差错率 packet error ratePIR 分组插入率 packet insertion ratePLCP 物理层会聚协议 Physical Layer Convergence ProtocolPLR 分组丢失率 packet loss ratePMD 物理媒体相关（子层） Physical Medium DependentPPP 点到点协议 Point to Point ProtocolPPTP 点对点隧道协议PRM 协议参考模型 Protocol Reference ModelPRN 分组无线网 Packet Radio NetworkPSN 分组交换节点 Packet Switch NodePSTN 公用电话交换网 Public Switched Telephone NetworkRARP 逆向地址解析协议 Reverse Address Resolution ProtocolRAS 远程访问服务器RFC 请求评注 Request for CommentsRMON 远程网络管理Router 路由器RPC 远程过程调用 Remote Procedure CallRSVP 资源重复利用协议RTP 接收和发送端口RTS 往返样本 Round Trip SampleRTS 剩余时间标签SAP 业务接入点 Service Access PointSAP 服务公告协议 Service Advertising ProtocolSAR 分段和重组(子层) Segmentation and ReassemblySDH 同步数字系列 Synchronous Digital HierarchySDLC 同步数据链路控制(协议) Advanced Data Communication Control Procedure SDTV 标准数字电视SDU 业务数据单元 Service Data UnitSIPP 增强的简单因特网协议 Simple Internet Protocol PlusSLIP 串行线路IP Serial Line Interface ProtocolSMDS 交换式多兆比特数据业务 Switched Multimegabit Data ServicesSMF 单模光纤 Single-mode FiberSMT 站点管理 Station ManagementSMTP 简单邮件传输协议 Simple Mail Transfer ProtocolSNA 系统网络体系结构 System Network ArchitectureSNMP 简单网络管理协议 Simple Network Management ProtocolSNR 信噪比 Signal-Noise ratioSONET 同步光纤网络 Synchronous Optical NetworkSTM 同步传输方式 Synchronous Transfer ModeSTP 屏蔽双绞线 Shielded Twisted PairSTS 同步传输信号 Synchronous Transport SignalSVC 交换虚电路 Switched Virtual CircuitSwitch 交换机TCP 传输控制协议 Transmission Control ProtocolTDM 时分多路复用 Time Division MultiplexingTFTP 单纯文件传输协议 Trivial File Transfer protocolTelnet 远程登录协议TIP 终端接口处理机 Terminal Interface ProcessorTP 双绞线 Twisted PairTSAP 传输层服务访问点 Transport Service Access PointUDP 用户数据报协议 User Datagram ProtocolUSB 通用串行总线 Universal Serial BusUTP 非屏蔽双绞线 Unshielded Twisted PairVAN 增值网 Value Added NetworkVBR 可变比特率 Variable Bit RateVCC 虚信道连接 Virtual Channel ConnectionVLAN 虚拟局域网 Virtual LANVLSI 超大规模集成电路VOD 点播图像 Video on DemandVPC 虚路径连接 Virtual Path ConnectionVPI 虚路径标识 virtual path identifierVPN 虚拟专用网络 Virtual Private NetworkVRML 虚拟现实造型语言 Virtual Reality Modeling Language VTP 虚拟隧道协议WAN 广域网 Wide Area NetworkWDM 波分多路复用 Wavelength Division MultiplexingWWW 万维网 World Wide Web。
可编程控制器的数据库系统—中英文翻译资料大学论文
Database Systems for Programmable Logic Con trollersIn this paper, we ide ntify the database issues associated with programmable logic con trollers (PLC), special-purpose computers used in scie ntific and in dustrial applications, e.g. in factories in manufacturing environments. We propose as a PLC database system a single-user,real-time, scalable main-memory-only relational databasesystem with a two-level architecture hav ing historical data modeli ng and man ipulatio n capabilities, and query process ing tech niq ues in corporati ng time- an d/or error-constrained query evaluation. We revise the ladder logic Ianguage, the most com mon PLC Ian guage, to in corporate data man ipulati on Ian guage in structi ons. We add a separate time comp onent into the PLC processor sca n time to han dle database updates, backup, in tegrity en forceme nt and data archival issues.1. In troduct ionA programmable logic controller (PLC) is a special-purpose computer used within real-time scie ntific comput ing systems, and in dustrial con trol systems, say, the automated con trol of a factory's mach inery - the running example used in this paper. This paper is a positi on paper that proposes a PLC database system and discusses its features. In doing so, we touch bases with a nu mber of basic database topics, and, thus, freque ntly refer to other work for details.PLCs are mostly used in manu facturi ng en vir onments - hen ce, the choice of our running example. However, PLCs are also used in scientific applications for signal data gathering and preliminary data processing. Thus, we think that for some scientific applications, a PLC databasemay also serve as a local/transient part of a larger scie ntific database.With the rapid advances in computer hardware and falling memory prices, in rece nt years, the capabilities of the new PLCs in the marketplace have bee n in creas ing dramatically. This paper is a positi on paper that argues that a PLC software can now con ta in a database system to greatly in crease its fun ctio nality. We propose the architecture in Figure 1 as the architecture of an environment where real-time data gatheri ng (from multiple sen sors) and real-time data man ipulati on takes place. We now list the adva ntages of hav ing a database system directly in side a PLC.(1) Data Modeli ng Tech niq ues : The in put and output buffers represe nt a rather unorgani zed tran sie nt model of the real world, and hen ce, carl be modeled better using the traditi onal data modeli ng tech niq ues of databases.(2) Historical Databases: PLCs rout in ely deal with differe nt versi ons of data over time. Therefore, historical data modeli ng tech niq ues as well as historical data man ipulati on tech niq ues can replace the ad hoc ways of man ipulat ing historical data in PLCs.(3) User-Frie ndly In terfaces : Prese ntly in the marketplace, the PLC software and in dustrial termi nals allow a limited display of messages and variable-data in formatio n in memory. For example, the con tact histogram fun cti on displays the on/off history of a specific mai n memory.(4) Han dli ng Large Volumes of Data : With the added capabilities of a database and a query Ian guage, the PLC may an alyze much larger volumes of data.(5) Data Reducti on and Compacti on at the PLC Level : Prese ntly, for further an alysis or simply due to various regulati ons, data collected by PLCs get tran smitted and stored into a host computer file using an architecture show n..Since the prese nt PLCs cannot satisfactorily an alyze most data, they simply tran smit data to the host computer. I n some scie ntific experime nts and applicati ons, the data gathered is so large that argume nts have bee n raised for "processi ng the data on-the-fly" duri ng the executi on of an experime nt/tra nsacti on [SSDB 86](a) Real-Time Database : The data in the in put buffer must be sca nn edwith in reas on ably short "real-time" in tervals ranging from microsec onds to sec on ds. Therefore,resp on ses to queries must be guara nteed to be less tha n a certa in "realtime" time bound, almost always less tha n 5 to 10 sec on ds.(b) Mai n Memory Database: Microsec on ds/sec on dsquery resp on serestrictio ns n ecessitate main-memory-only databases.(c) Scalable Database : Once the en vir onment of a PLC and the requireme nts of the associatedapplicatio n program are determ in ed, the possible query types to the database stay fixed for a reas on ably long period of time. Si nee the resp onse time of queries is of utmost importa nee, the DBMS should be scaled so that only the n eededrouti nes/fu nctions (e.g., access methods, data structures, etc.) are in corporated.In secti on 2, we discuss the gen eral characteristics PLCs, and briefly prese nt the ladder logic Ianguage. Section 3 discusses the features of the proposed database system for PLCs.In general, the PLC hardware is mostly custom-built with occasional off-the-shelf hardware, and con sists of a CPU (or multiple CPUs), main memory, an "in dustrial term in al", and high- and medium-speed data com muni cati ons hardware. The size of the main memory ran ges from 16K bytes (of 5 to 10 years ago) to 8M bytes (of the prese nt time).Although the CPU has an in structio n set similar to those found in CPUs of 16-bit and 32-bit mach in es, it is especially equipped with fast bit man ipulati on in struct ions. The in dustrial termi nal comes with a special keyboard to make the program ming of the PLC easier an d/or to in terve ne with the applicati on program.The PLC software consists of an operating system (ranging from a very simplistic mon itor (of ten years ago) to a sophisticated real-time operati ng system (of the rece nt time)), high-speed com muni cati ons software for com muni cat ing with I/O processors,medium-speed com muni cati ons software to the in dustrial termi nal and to other "i ntellige nt" devices.Both gen eral-purpose computers and PLCs are used for in dustrial con trol [Star 87].However, they differ in the program ming Ian guages that they use, en vir onmen tal specifications, and their user types. PLCs are rugged, and work in hostile environments with no special climate controls, tolerating extremes of temperature (60 °C), humidity (95%) and air contamination. Users of PLCs include the original programmers of the application programs, as well as plant electricians and maintenance pers onn el, who are accustomed to relay-type con trolli ng en vir onmen ts.A rung is an ordered set of PLC in structi ons draw n on a si ngle line. In struct ions on a rung are classified as in put in structi ons (those that mon itor the in put buffer) and output in struct ions (those that set the output buffer), and are executed from left to right, seque ntially (Please see figure 4). A PLC applicatio n program con sists of a main program and a set of subrout in es, each of which containing an ordered set of rungs To summarize, the applicati on programmer deals with actual (realtime) clock times, and needs to have precise estimates for program sca n times and I/O sca n times. For time estimati ons, the PLC manu facturers supply in formatio n such as 4 msec onds for 1000 ladder logic in structi ons, and 1 msec onds for copy ing 256 words into an in put buffer duri ng the I/O sca n. In most applicati ons, the processor sca n time is kept below 10 sec on ds.Thus,databasema nipulati on in struct ions also n eed to have precise time limits available to (or set by) users.2. ArchitectureWe propose a two-level, sin gle-user databasesystem architecture as show n in figure 6. We have omitted from our architecture the exter nal model of the traditi onal databasearchitecture not becausePLCs are not powerful, but becausec on curre ntly running application programs using different views create problems in accurately estimati ng the applicati on program scan times. That is, i n a multitask ing en vir onment where tasks compete for the resources such as database relati ons and com muni cati on lin es, decid ing a sin gle top-to bottom executi on time of a task in actual time is rather difficult (if at all possible).As far as the hardware comput ing power is concern ed, the prese nt day PLCs are as powerful as pers onal computers (and, in deed, in some rece nt products,PLCs are pers onal computers), and can certa inly support multiple in dustrial termin als and data shari ng among the applicati on programs.3. Data Modeli ng IssuesThe traditi onal data modeli ng tech niq ues directly apply to PLC databases. There is no reas on why, say, the En tity-Relatio nship Model [Che n 76] of the data in the PLC database cannot be desig ned. All the well-k nown adva ntages of data modeli ng [ToeF 82] directly carry over to the PLC database en vir onment, and will not be elaborated here. As for the conceptual model of our prototype effort, we have chosen the relatio nal model. The PLC en vir onment n aturally deals with historical data, e.g., the last readi ng of a grinding mach ine sen sor, its value yesterday, etc.. Aga in, there are various historical data modeling approaches [SnoA 85] in the literature and, theoretically, any one of them is acceptable.Example. Con sider a set of furn aces that produce high-precisi on airpla ne parts. There are two entity relations, FURNACE and PART, and one time-varying relati on shiprelati on PRODUCES as described in figure 7. Please n ote that PRODUCES relation has tuple timestamping with BEGIN-TIME and END-TIME attributes.4. DBMS IssuesThere are a number of issues that need to be resolved in a time-constrained, sin gle user DBMS en vir onment. These are(a) Data Archival.(b) Database Backup.(c) Database In tegrity en forceme nt.5. Query Process ing IssuesThe conventional database management systems (DBMS) do not have the capability of dyn amically meeti ng the time con stra ints whe n the amount of data is too large to process within a give n time quota. Our approach is, for a give n time quota, to take an appropriate amount of sample data such that the set of sampled data is guara nteed to be processible by the DBMS within the give n.Some basic PLC in structi ons have also bee n exte nded to in crease their fun cti on ality.For example, we have exte nded the "exam ine logic switch" in structi ons, the Exami ne Input Closed (XIC) and the Exami ne In put Ope n (XIO) [AB 84, AB 85], to test the logical value of a propositi onal calculus formula, rather tha n testi ng a bit value corresponding to the condition of a physical I/O. An "examine F" instruction causesthe formula F to be evaluated and the role value is the n exam ined as in the basic exam ine in structi ons. In gen eral, the formula F may con tai n a con sta nt, a variable, a comp onent of a tuple being sca nned by the poin ter, and fiE) where f is an aggregate fun ctio n and E is a relati onal algebra expressi on. The fun ctio nality of the PLC Timer and Coun ter in structi ons have also bee n enhan ced. Usually con diti oned by "exam ine" in struct ions, timers and coun ters keep track of timed in tervals or eve nts; the number of timed intervals or events to be counted is set in the preset value variables [AB 85, AB 84]. With the in troduct ion of a time dime nsion into the database, eve nts and in tervals can also be "co un ted" using database queries.6 .Query Process ing IssuesThe conventional database management systems (DBMS) do not have thecapability of dyn amically meeti ng the time con stra ints whe n the amount of data is too large to process within a give n time quota. Our approach is, for a give n time quota, to take an appropriate amount of sample data such that the set of sampled data is guaranteedto be processible by the DBMS within the given time quota, and, exact time-cost formulas can be derived.Clearly, the more stages the query processor goes through, the more overhead is invo Ived in the run-time estimati on approach. This implies that, at each stage, as large an amount of time as possible should be allocated to reduce the nu mber of stages. On the other hand, allocat ing large amounts of time has a higher risk of overspe nding the time quota and may end up wasti ng a large amount of time, especially in a hard time constrained environment [AbGM 88, StZa 88]. The hard time constrained environments denote those environments where overspending the time quota is strictly not allowed. Therefore, when overspending happens, the query has to be aborted prematurely and the amount of time used in the last stage is considered wasted.7.Other IssuesThe issue of in complete in formatio n in the PLC database is also being in vestigated.Quite ofte n, the sen sors give in complete in formati on, usually a range for a readi ng. On those occasi ons, the in complete data is only known to be within some range of values.We represe nt an in complete data item as an in terval which contains the unknown value.We have finished the implementation of the first version of a PLC database [-Liu89] hav ing some of the features summarized in sect ion 3. The system has bee n developed on SUN workstati ons using the C Ian guage. We are pla nning to tran sport it into a PLC, and evaluate its performa nee.Refere nces[AB84] PLC-3 Programmable Controller Programming Manual, Allen-Bradley Co., 1984.[AB85] PLC-5/15 Programmable Controller Processor Manual, Allen-Bradley Co., 1985.[Chri83] Christodoulakis, S., "Estimati ng Record Selectivities", In formationSystems,© 8, 1983.[HP88] Hewlett-Packard Announ ceme nt of the HP RTDBS, Sept. 1988.[Klug81] A. Klug, "ABE - A Query Lan guage for Con struct ing Aggregate-by-Example", 1st LBL Workshop on Statistical Database Management, Dec. 1981.[Ullm88] J.D Ullman, "Principles of Database and Knowledge-Base Systems", Computer Scie nee Press, 1988.[SSDB86] Panel on Scie ntific Databases, Third Int. Workshop on Statistical a nd SCie ntific Database Man ageme nt, 1986.[Star87] R.J. Staron, "A Toolset to Develop Programmable Controller Systems",u npublished ma nuscript, Alle n-Bradley Co., March 1987.可编程控制器的数据库系统在这篇文章中，我们确定一种在科学和工业上有特别应用目的的计算机一一可编程控制器(PLC )数据库系统的相关问题。
中英文翻译数据库基础精品
Database FundamentalsIntroduction to DBMSA database management system (DBMS) is an important type of programming system, used today on the biggest and the smallest computers. As for other major forms of system software, such as compilers and operating systems, a well-understood set of principles for database management systems has developed over the years, and these concepts are useful both for understanding how to use these systems effectively and for designing and implementing DBMS's. DBMS is a collection of programs that enables you to store, modify, and extract information from a database. There are many different types of DBMS's, ranging from small systems that run on personal computers to huge systems that run on mainframes.There are two qualities that distinguish database management systems from other sorts of programming systems.1) The ability to manage persistent data, and2) The ability to access large amounts of data efficiently.Point 1) merely states that there is a database which exists permanently; the content of this database is the data that a DBMS accesses and manages. Point 2) distinguishes a DBMS from a file system, which also manages persistent data.A DBMS's capabilities are needed most when the amount of data is very large, because for small amounts of data, simple access techniques, such as linear scans of the data, are usually adequate.While we regard the above two properties of a DBMS as fundamental, there are a number of other capabilities that are almost universally found in commercial DBMS's. These are:(1) Support for at least one data model, or mathematical abstraction through which the user can view the data.(2) Support for certain high-level languages that allow the user to define the structure of data, access data, and manipulate data.(3) Transaction management, the capability to provide correct, concurrent access to the database by many users at once.(4) Access control, the ability to limit access to data by unauthorized users, and the ability to check the validity of data.(5) Resiliency, the ability to recover from system failures without losing data.Data Models Each DBMS provides at least one abstract model of data that allows the user to see information not as raw bits, but in more understandable terms.In fact, it is usually possible to see data at several levels of abstraction. At a relatively low level, a DBMS commonly allows us to visualize data as composed of files.Efficient File Access The ability to store a file is not remarkable: the file system associated with any operating system does that. The capability of a DBMS is seen when we access the data of a file. For example, suppose we wish to find the manager of employee "Clark Kent". If the company has thousands of employees, It is very expensive to search the entire file to find the one with NAME="Clark Kent". A DBMS helps us to set up "index files," or "indices," that allow us to access the record for "Clark Kent" in essentially one stroke no matter how large the file is. Likewise, insertion of new records or deletion of old ones can be accomplished in time that is small and essentially constant, independent of the file length. Another thing a DBMS helps us do is navigate among files, that is, to combine values in two or more files to obtain the information we want.Query Languages To make access to files easier, a DBMS provides a query language, or data manipulation language, to express operations on files. Query languages differ in the level of detail they require of the user, with systems based on the relational data model generally requiring less detail than languages based on other models.Transaction Management Another important capability of a DBMS is the ability to manage simultaneously large numbers of transactions, which are procedures operating on the database. Some databases are so large that they can only be useful if they are operated upon simultaneously by many computers: often these computers are dispersed around the country or the world. The database systems use by banks, accessed almost instantaneously by hundreds or thousands of automated teller machines (ATM), as well as by an equal or greater number of employees in the bank branches, is typical of this sort of database. An airline reservation system is another good example.Sometimes, two accesses do not interfere with each other. For example, any number of transactions can be reading your bank balance at the same time, without any inconsistency. But if you are in the bank depositing your salary check at the exact instant your spouse is extracting money from an automatic teller, the result of the two transactions occurring simultaneously and without coordination is unpredictable. Thus, transactions that modify a data item must “lock out” other transactions trying to read or write that item at the same time. A DBMS must therefore provide some form ofconcurrency control to prevent uncoordinated access to the same data item by more than one transaction.Even more complex problems occur when the database is distributed over many different computer systems, perhaps with duplication of data to allow both faster local access and to protect against the destruction of data if one computer crashes.Security of Data A DBMS must not only protect against loss of data when crashes occur, as we just mentioned, but it must prevent unauthorized access. For example, only users with a certain clearance should have access to the salary field of an employee file, and the DBMS must be able associate with the various users their privileges to see files, fields within files, or other subsets of the data in the database. Thus a DBMS must maintain a table telling for each user known to it, what access privileges the user has for each object. For example, one user may be allowed to read a file, but not to insert or delete data; another may not be allowed to see the file at all, while a third may be allowed to read or modify the file at will.DBMS TypesDesigners developed three different types of database structures: hierarchical, network, and relational. Hierarchical and network were first developed but relational has become dominant. While the relational design is dominant, the older databases have not been dropped. Companies that installed a hierarchical system such as IMS in the 1970s will be using and maintaining these databases for years to come even though new development is being done on relational systems. These older systems are often referred to as legacy systems.数据库基础DBMS 简介数据库管理系统是编程系统中的重要的一种，现今可以用在最大的以及最小的电脑上。
JDBC(数据库连接)外文翻译及原文
JDBC (Java Data Base Connectivity)JDBC (Java Data Base Connectivity,) is a SQL statement for the implementation of the Java API, for a variety of relational databases to provide a unified visit by a group, it’s using Java language preparation classes and interface. JDBC for tools / database development provides a standard API, which can build more sophisticated tools and interfaces to database developers. Pure Java API can be used to prepare database applications, at the same time, JDBC is also a brand name. With JDBC, data sent to the various relationships SQL statement is a very easy matter. In other words with JDBC API, we do not have to visit a Sybase database to write specialized procedures, visit the Oracle database specifically to write a program, or visit Informix database and the preparation of another procedure, programmers should use the JDBC API to write a procedure enough, it can be sent to the corresponding SQL database calls. Meanwhile, the Java language and JDBC to integrate non-programmers do not have to, with a platform for the preparation of different applications, just write it again in the process can be run on any platform, which is the Java language "Write once, run everywhere" advantage. Java database Connect Architecture for Java application of the standard method of connecting to the database. JDBC is the case of Java programmers API, and the realization of the database connection is the case of service providers interface model.As API, JDBC program development for the provision of standard interfaces, and database vendors and third-party middleware vendors to achieve connectivity and database provides a standard method. JDBC use the existing SQL standard - Support and other databases and connectivity standards, such as bridge between ODBC. JDBC achieve all these objectives and standards for a simple, high-performance and strict definition of achieving type interface. Java with a solid, safe, easy to use, easy to understand and can be automatically downloaded from the Internet and other characteristics of the preparation of the outstanding database application language. Need is a Java application Database with a variety of different procedures for a dialogue between the methods. The JDBC is the mechanism for such purposes. Java JDBC expanded functionality. For example, with Java and JDBC API Applet can be issued containing the page, and the applet may use the information from remote databases enterprises can also use JDBC to all staff through the Intranet will be connected to one or more Internal database (even if those staff computers are used by Windows, Macintosh, and UNIX, and other various operating systems). As more and more programmers using Java Programming language, Java from the convenient access to the database requirements areincreasing. MIS administrators like the combination of Java and JDBC, because it makes it easy to disseminate information and Economy. Enterprises can continue to use their installed database, and can easily access information, even if this information is stored in the different database management systems. The development of new procedures is a very short period. An Equipment and version control will be greatly simplified. Programmers can prepare only what applications or updated only once, and then put it on the server, and then on any person can get the latest version of the application. Sales for the business information services, Java and JDBC for external customers with better access to information update method.First, the use of JDBCSimply put, JDBC to do three things: establish a connection with the database, send SQL statements and the results. The following codes are the basic examples:Connection con = DriverManager.getConnection ( "jdbc: odbc: wombat," "login""Password");Statement stmt = con.createStatement ();ResultSet rs = stmt.executeQuery ( "SELECT a, b, c FROM Table1");While (rs.next ()) {Int x = rs.getInt ( "a");String s = rs.getString ( "b");Float f = rs.getFloat ( "c");}Based on the above code JDBC database access to a summary of the classic, of course, in this part of the follow-up section we will do a detailed analysis.Second, JDBC APIJDBC is a "low-level" interface, that is, it calls for direct SQL commands. In this respect it functions very good, and other than the easy-to-use database connectivity API, but it also has been designed as a basis interface, it can be established on the High interface and tools. High interface is "user-friendly" interface, which uses a more comprehensible and more convenient API. This API is converted in the behind-the-scenes such as JDBC such a low-level interface. In the relational database "object / relationship" mapping, each row in the table corresponding to the category of an example, the value of each column the examples should be an attribute. Therefore, programmers can directly operate on the Java objects; SQL for data access call will be "under the guise of" automatically generated. They can also be more complex mapping, for example, a number of rows in the table integrated into a Java class. With the interest of the people of JDBC the growing, and more and more developers have been using JDBC-based tools So that the preparation process more easily. Programmers has been trying to make in the preparation of end-user database access has become moresimple applications. For example, applications can provide a choice of According to the mandate of the menu. Task was chosen, the application will be given tips and blank selected for the task of completing the implementation of the necessary information. Application procedures for the importation of the required information will automatically call for SQL Order. In such a process with the assistance, even if they do not understand the fundamental SQL syntax, but also can perform database tasks.Third, JDBC and ODBC compared with other APICurrently, Microsoft's ODBC API is the most widely used for the visit of the relational database programming interface. It can connect almost all platforms almost all databases. For What Java does not use ODBC? The answer to this question is: Java can use ODBC, but preferably with the help of the JDBC to JDBC-ODBC Bridge in the form of use of this point, we later say. The problem now has become: "Why do we need JDBC?" The answer is clear: ODBC not suitable for direct use in Java, because it uses C language interface. Transferred from Java C code in the local security, achieved solid and procedural aspects of the automatic transplantation has many shortcomings. From ODBC C API Java API to the literal translation is not advisable. For example, Java does not guide, and it has ODBC indicators used very widely (including very error-prone Guidelines "void *"). You can imagine JDBC will be converted into the object-oriented interface to the ODBC, and the object-oriented interface to make it easier for Java programmers to receive. ODBC is difficult to learn. It simple and advanced features of the mix, and even the simple query, the options are extremely complex. On the contrary, JDBC to guarantee simple function of simplicity, At the same time, if necessary, to allow the use of advanced features. The opening of "pure Java" mechanism needs such as JDBC Java API. If you use ODBC, it is necessary to manually will be ODBC driver management and driver installation in each client machines. If completely written in Java JDBC Driver in all the JDBC code on the Java platform (from the computer network to the mainframe) can be Automatic installation, and guarantee the safety of transplantation.In short, JDBC API for SQL abstract and basic concepts of Java is a natural interface. It is built on ODBC rather than starting from scratch. Therefore, programmers will be familiar with ODBC JDBC found very easy to use. ODBC JDBC retains the basic design features; In fact, the two interfaces are based on the X / Open SQL CLI (call-level interface). Among them the largest district, another is: Java JDBC to style and based on the merits and optimization, more easy to use.At present, Microsoft has introduced a new addition to ODBC API: RDO, ADO and OLE DB. These design in many ways and JDBC is the same, that is, they are the object-oriented Based on the database interface and can be achieved on ODBC in the category.But the interface, we did not see any special features that make their choice we need to turn to alternative ODBC, especially in the ODBC Flooding Has been established procedure for better market conditions. They also is the largest in the ODBC add a decoration only. Forth, JDBC on the B / S and C / S mode supportJDBC API supports both the two-tier model of database access (C / S), but has also supported the three-tier model (B / S). In the two-tier model, Java applet or application will be directly into the database to dialogue. This will require a JDBC driver to visit with the specific database management systems to communicate. Users of SQL statements sent to the database, and its results will be returned to user. Database can be located on another computer, users connected to the above network. This is called client / server configuration, user's computer for the client, providing database computing Machines for servers. Intranet network can be (it can be linked to company staff), it can also be an internet.In the three-tier model, the order was first sent to the "middle layer", and then by the SQL statement it sent to the database. Database on SQL statement processed and the results sent back to the middle Layer, the middle layer then the results returned to users. MIS managers have discovered the three-tier model is very attractive, because the middle layer can be used to control access to company data and can be used for the newer types. In Another advantage of inter-layer, the user can use the easy-to-use high-level API, and the middle layer will be converted to its corresponding low-level calls. Finally, in many cases under the three-tier structure can provide some performance on the benefits.So far, the middle layer are usually in C or C + + language to prepare such, the implementation of these languages faster. However, with the most optimized compiler (it to switch to Java byte code Efficient in the specific machine code) the introduction, use Java to achieve middle layer will be more practical. This will be a big step forward, it enables people to take full advantage of the many Java Advantages (such as robust, multi-threaded, and security features). For Java JDBC from the middle layer to access a database is very important.Fifth, SQL consistencyStructured Query Language (SQL) relational database access is the standard language. The tricky part is: Although most of the DBMS (database management system) to use the basic functions Standard forms of SQL, but they are not consistent with the recent higher standard definition of the functions of SQL syntax or semantics. For example, not all databases support stored procedures or external connections, it More support this function in the database and mutually inconsistent. It is hoped that the SQL standard that the real part to expanding to include more and more functions. But at the same time it must support JDBCAPI With the existing SQL.JDBC API solution to this problem is to allow a way for any string has been reached by the driver on the DBMS. This means that applications can use any number of SQL Functional, but it must take the risk: it is possible in some DBMS errors. In fact, applications for SQL even if not, or that it may be for a specific DBMS Design SQL dedicated derivatives (for example, documents or images enquiries). JDBC deal with the issue of consistency SQL second method is to provide ODBC-style escape clause, which will in the follow-up Part of the discussion. Escape for a few common grammatical differences SQL provides a standard syntax JDBC. For example, the date has been stored text and the process of calling all escaped grammar. For complex Miscellaneous applications, JDBC third method used to deal with the issue of consistency in its SQL Database Meta Data interface to use DBMS on the description of information, thus enabling application - Each DBMS order to adapt to the requirements and functional. As JDBC API will be used to develop advanced tools and database access API, API basis, it must also pay attention to all of its superstructure consistency. "TM with JDBC standards," representatives of the JDBC users can rely on the standard-level functions. To use this statement, the driver must be at least support the ANSI SQL-2 Entry Level (ANSI SQL-2 represent the United States National Bureau of Standards in 1992, the standards adopted. Entry Level SQL functions on behalf of a specific list). Driver developers can be carried by the JDBC API Testing kits to determine whether the driver of their compliance with these standards. "TM with JDBC standards," said the JDBC providers have been adopted to achieve the Java Soft the conformance testing. These tests will check the consistency of the definition of JDBC API all the classes and methods exist, as far as possible, to check whether the procedures SQL Entry Level function. Of course, these tests not entirely, but now has no intention of Java Soft the various providers to the realization of superscript level. However, this definition of consistency can indeed achieve the JDBC provide a certain degree of credibility. As more and more Database providers, connecting providers, Internet providers and application programming Members of the JDBC API acceptance, JDBC is also rapidly becoming the standard Java database access.Sixth, JDBC entrance - Establishment of connectionYou need to do the first thing is you want to use the DBMS and the establishment of a connection. This includes two steps: loading drivers and establish a connection.Loading driversLoading drivers need only a very simple line code. For example, you want to use JDBC-ODBC Bridge Driver, loading it with the following code:Class.forName ( "sun.jdbc.odbc.JdbcOdbcDriver");Document your driver will tell you should use the class name. For example, if the category were jdbc.DriverXYZ, you will be used to code the following code loading drivers: Class.forName ( "jdbc.DriverXYZ");You do not need to create an instance of the class driver and register it with DriverManager, because calls will be automatically loaded Class.forName Driver category. If you had to create their own examples, you will create an unnecessary copy, but it will not do any harm.Loading Driver category, they can be used to connect with the database.ConnectionThe second step is to use the appropriate driver of the establishment of a connection with the DBMS. The following code is the general practice:Connection con = DriverManager.getConnection (url, "myLogin", "myPassword");This step is very simple and the most difficult is how to provide url. If you are using JDBC-ODBC Bridge, JDBC URL will be jdbc: odbc beginning: the remaining URL is usually your data source name, or database system. Therefore, assuming that you are using ODBC access to a man named "Fred" ODBC data source, your JDBC URL is jdbc: odbc: Fred. "MyLogin" and "myPassword" landing DBMS are the replacement for your user name and password. If you landing database system are the user name "Fernanda" Password "J8", only the following two lines of code can establish a connection:String url = "jdbc: odbc: Fred";Connection con = DriverManager.getConnection (url, "Fernanda," "J8");If you are using the third-party developers of the JDBC driver, the documents will tell you what subprotocol use is in the JDBC URL on the back of some jdbc. For example, if a driver developers registered as a subprotocol acme, JDBC URL in the first and second part will be jdbc: acme. Drivers will tell you the remaining documents JDBC URL format. JDBC URL last part of the positioning is to provide the information in the database.If you load the driver identification provided to the JDBC URL DriverManager.getConnection, that driver will be the establishment of a JDBC URL link to a specific DBMS. As the name indicates, DriverManager class management behind the scenes for you to connect all the details. Unless you are writing drivers, you may not use any other method such, the general programmers need to use such a direct approach is the only DriverManager.getConnection.DriverManager.getConnection method returns an open connection, you can use this link to create JDBC statements and send SQL statements to the database. In the preceding example, the object is a con opened connection, and we will in the future example, use it.外文翻译JDBC（数据库连接）JDBC（Java Data Base Connectivity,java数据库连接）是一种用于执行SQL语句的Java API，可以为多种关系数据库提供统一访问，它由一组用Java语言编写的类和接口组成。
db开头的英文词组
db开头的英文词组数据库（Database）是现代计算机系统中的一个重要组成部分，广泛应用于各个领域。
在数据库中，我们经常会遇到以"DB"开头的英文词组。
本文将介绍几个常见的DB开头的英文词组及其应用。
DBMS（Database Management System）DBMS是数据库管理系统的缩写，它是一种软件系统，用于管理数据库中的数据。
DBMS允许用户创建、访问、更新和维护数据库，提供了数据存储、数据操作、数据安全等功能。
常见的DBMS包括MySQL、Oracle、SQL Server等。
DBA（Database Administrator）DBA是数据库管理员的缩写，他们负责数据库的设计、安装、配置和维护工作，确保数据库系统的正常运行。
DBA还负责监控数据库的性能，优化数据库结构，确保数据的安全性和完整性。
DBS（Database System）DBS是数据库系统的缩写，它是由DBMS、数据库和应用程序组成的一个整体。
数据库系统是为了高效地管理和组织大量数据而设计的，它可以提供数据共享、数据一致性、数据安全等功能。
DBDC（Database Distributed Computing）DBDC是数据库分布式计算的缩写，它是一种数据库架构，将数据库分布在多台计算机上，通过网络连接进行数据交换和共享，提高了数据库的性能和可靠性。
DBDC常用于大规模的企业应用系统或互联网应用中。
DBaaS（Database as a Service）DBaaS是数据库即服务的缩写，它是一种云计算服务模式，在云平台上提供数据库服务。
用户无需关心数据库的底层架构和维护工作，只需通过网络访问和使用数据库。
DBaaS提供了简单、快速和灵活的数据库解决方案，降低了数据库的运维成本。
DBR（Database Replication）DBR是数据库复制的缩写，它是一种数据库备份方案，将数据库的数据复制到其他服务器上以提供冗余和灾备能力。
计算机网络中英文互译
计算机网络中英翻译ACK (ACKnowledgement) 确认帧ADSL (Asymmetric Digital Subscriber Line) 非对称数字用户线AN (Access Network ）接入网ANSI (American National Standards Institute) 美国国家标准协会AP (Access Point) 接入点API (Application Programming Interface) 应用编程接口APNIC (Asia Pacific Network Information Center) 亚太网络信息中心ARP （ Address Resolution Protocol ）地址解析协议ARPA (Advanced Research Project Agency)美国国防部远景研究规划局（高级研究计划署）ARQ (Automatic Repeat reQuest) 自动请求重发ATM (Asynchronous Transfer Mode) 异步传递方式ATU (Access Termination Unit) 接入端接单元ATU-C (Access Termination Unit Central Office ）端局接入端接单元ATU-R (Access Termination Unit Remote) 远端接入端接单元AUI (Attachment Unit Interface ）连接接口单元AWT （ Abstract Window Toolkit ）抽象窗口工具箱BECN (Backward Explicit Congestion Notification) 反向显式拥塞通知BER (Basic Encoding Rule) 基本编码规则BGP (Border Gateway Protocol) 边界网关协议BSA (Basic Service Area) 基本服务区BSS (Basic Service Set) 基本服务集BNA 宝来网络体系结构CAC (Connection Admission Control) 连接准许控制CAP (Carrierless Amplitude Phase) 无载波振幅相位调制CATV (Community Antenna TV, CAble TV) 有线电视CBR （ Constant Bit Rate ）恒定比特率CCIR (Consultative Committee，International Radio) 国际无线电咨询委员会CCITT (Consultative Committee, International Telegraph and Telephone)国际电报电话咨询委员会CCP 通信控制处理机CDM (Code Division Multiplexing) 码分复用CDMA (Code Division Multiplex Access) 码分多址CNNIC (Network Information Center of China) 中国互联网络信息中心CRC (Cyclic Redundancy Check) 循环冗余检验CSMA/CD (Carrier Sense Multiple Access ／ Collision Detection)载波监听多点接入/碰撞检测CSU/DSU （ Channel Service Unit/Data Service Unit) 信道服务单元／数据服务单元CTD (Cell Transfer Delay) 信元传送时延DACS (Digital Access and Cross-connect System) 数字交接系统DCA 数据通信体系结构DCE (Data Circuit-terminating Equipment) 数据电路端接设备DE (Discard Eligibility) 丢弃指示DES (Data Encryption Standard) 数据加密标准DHCP (Dynamic Host Configuration Protocol) 动态主机配置协议DLCI (Data Link Connection Identifier) 数据链路连接标识符DMT (Discrete Multi-Tone) 离散多音（调制）DNS (Domain Name System) 域名系统DNA 数据网络系统结构DSL (Digital Subscriber Line) 数字用户线DSLAM (DSL Access Multiplexer) 数字用户线接入复用器DSSS (Direct Sequence Spread Spectrum) 直接序列扩频DTE (Data Terminal Equipment) 数据终端设备DVMRP (Distance Vector Multicast Routing Protocol) 距离向量多播路由选择协议DWDM (Dense WDM) 密集波分复用EGP (External Gateway Protocol) 外部网关协议EIA (Electronic Industries Association ）美国电子工业协会ESP (Encapsulating Security Payload) 封装安全有效载荷ESS 伍 xtended Service Set) 扩展的服务集FCS (Frame Check Sequence) 帧检验序列FDDI (Fiber Distributed Data Interface ）光纤分布式数据接口FDM (Frequency Division Multiplexing) 频分复用FEC (Forwarding Equivalence Class) 转发等价类FEC (Forward Error Correction) 前向纠错FHSS (Frequency Hopping Spread Spectrum) 跳频扩频FIFO （ First In First Out) 先进先出FQ (Fair Queuing) 公平排队FR (Frame Relay) 帧中继FSK (Frequency Shift Keying) 移频键控FTP (File Transfer Protocol ）文件传送协议FTTB (Fiber To The Building) 光纤到大楼FTTC (Fiber To The Curb ）光纤到路边FTTH (Fiber To The Home) 光纤到家FTTD (Fiber To The Desk) 光纤到桌面FTTZ(Fiber To The Zone ）光纤到小区FTTO (Fiber To The Office) 光纤到办公室FTTF (Fiber To The Floor) 光纤到楼层GIF (Graphics Interchange Format) 图形交换格式GII (Global Information Infrastructure) 全球信息基础结构，全球信息基础设施GFC （ Generic Flow Control) 通用流量控制GSM (Group Special Mobile) 群组专用移动通信体制HDLC (High-level Data Link Control) 面向比特的链路控制规程HDSL (High speed DSL) 高速数字用户线HEC (Header Error Control) 首部差错控制HFC (Hybrid Fiber Coax) 光纤同轴混合（网）HTML (HyperText Markup Language) 超文本置标语言HTTP (HyperText Transfer Protocol) 超文本传送协议IAB (Internet Architecture Board) 因特网体系结构委员会IAC （ Interpret As Command ）作为命令解释IAHC (Internet International Ad Hoc Committee ）因特网国际特别委员会ICMP （ Internet Control Message Protocol ）因特网控制报文协议IDEA (International Data Encryption Algorithm) 国际数据加密算法IEEE电气和电子工程师协会IESG (Internet Engineering Steering Group) 因特网工程指导小组IETF (Internet Engineering Task Force) 因特网工程部IFS (Inter Frame Space) 帧间间隔IGMP (Internet Group Management Protocol) 因特网组管理协议IGP (Interior Gateway Protocol) 内部网关协议IM (Instant Messaging) 即时传信IMAP (Internet Message Access Protocol) 因特网报文存取协议IMP （ Interface Message Processor) 接口报文处理机IP (Internet Protocol ）网际协议IR (InfraRed ）红外技术IRTF （ Internet Research Task Force ）因特网研究部ISDN (Integrated Services Digital Network) 综合业务数字网ISO （ International Organization for Standardization ）国际标准化组织ISOC (Internet Society) 因特网协会ISP （ Internet Service Provider) 因特网服务提供者ITU （ International Telecommunication Union ）国际电信联盟ITU-T （ ITU Telecommunication Standardization Sector) 国际电信联盟电信标准化部门JPEG (Joint Photographic Expert Group) 联合图像专家组标准KDC (Key Distribution Center) 密钥分配中心LAN (Local Area Network ）局域网LANE (LAN Emulation ）局域网仿真LAPB (Link Access Procedure Balanced) 链路接入规程（平衡型）LCP (Link Control Protocol) 链路控制协议LDP (Label Distribution Protocol) 标记分配协议LLC (Logical Link Control) 逻辑链路控制LSP (Label Switched Path) 标记交换路径LSR (Label Switching Router) 标记交换路由器MAC (Medium Access Control) 媒体接入控制MAN (Metropolitan Area Network) 城域网MAU (Medium Attachment Unit) 媒体连接单元MBONE (Multicast Backbone On the InterNEt ）多播主干网MBS (Maximum Burst Size ）最大突发长度MCR (Minimum Cell Rate ）最小信元速率 MCU (Multipoint Control Unit)多点控制单元MD (Message Digest) 报文摘要MDI (Medium Dependent Interface ）媒体相关接口MIB (Management Information Base) 管理信息库MIME (Multipurpose Internet Mail Extensions) 通用因特网邮件扩充modem 调制解调器MOTIF (Message Oriented Text Interchange System) 面向报文的电文交换系统MPEG (Motion Picture Experts Group) 活动图像专家组标准MPOA (MultiProtocol Over ATM) 多协议在 ATM 上运行MPLS (MultiProtocol Label Switching) 多协议标记交换MRU (Maximum Receive Unit) 最大接收单元MSS (Maximum Segment Size) 最长报文段MTU (Maximum Transfer Unit) 最大传送单元NAK (Negative AcKnowlegement) 否认帧NAP （ Network Access Point) 网络接入点N.ISDN (Narrowband-ISDN) 窄带综合业务数字网NAT (Network Address Translation ）网络地址转换NAV (Network Al location Vector) 网络分配向量NCP (Network Control Protocol) 网络控制协议NFS (Network File System) 网络文件系统NGI 下一代因特网计划NIA 网络适配器NIC (Network Interface Card) 网络接口卡、网卡NII (National Information Infrastructure) 国家信息基础结构，国家信息基础设施NLRI (Network Layer Reachability Information) 网络层可达性信息NNI (Network-Node Interface) 网络结点接口NSF (National Science Foundation) （美国）国家科学基金会NVT (Network Virtual Terminal ）网络虚拟终端ODBC （Open Database Connection）开放数据库互连OSF （Open Software Fundation ）开放软件基金会OSI （Open System Interconnection ）开放系统互联PBX （Private Branch eXchange ）用户交换机PCM (Pulse Code Modulation ) 脉冲编码调制PCN (Personal Communications Network ) 个人通信网络PCR （Peak Cell Rate ）峰值信元速率PCS 个人通信服务 Personal Communications ServicePDH 准同步数字系列PDA 个人数字助理 Personal Digital AssistantPDN 公用数据网 Public Data NetworkPDU 协议数据单元 Protocol Data UnitPER 分组差错率 packet error ratePIR 分组插入率 packet insertion ratePLCP 物理层会聚协议 Physical Layer Convergence ProtocolPLR 分组丢失率 packet loss ratePMD 物理媒体相关（子层） Physical Medium DependentPPP 点到点协议 Point to Point ProtocolPPTP 点对点隧道协议PRM 协议参考模型 Protocol Reference ModelPRN 分组无线网 Packet Radio NetworkPSN 分组交换节点 Packet Switch NodePSTN 公用电话交换网 Public Switched Telephone NetworkRARP 逆向地址解析协议 Reverse Address Resolution ProtocolRAS 远程访问服务器RFC 请求评注 Request for CommentsRMON 远程网络管理Router 路由器RPC 远程过程调用 Remote Procedure CallRSVP 资源重复利用协议RTP 接收和发送端口RTS 往返样本 Round Trip SampleRTS 剩余时间标签SAP 业务接入点 Service Access PointSAP 服务公告协议 Service Advertising ProtocolSAR 分段和重组(子层) Segmentation and ReassemblySDH 同步数字系列 Synchronous Digital HierarchySDLC 同步数据链路控制(协议) Advanced Data Communication Control Procedure SDTV 标准数字电视SDU 业务数据单元 Service Data UnitSIPP 增强的简单因特网协议 Simple Internet Protocol PlusSLIP 串行线路IP Serial Line Interface ProtocolSMDS 交换式多兆比特数据业务 Switched Multimegabit Data ServicesSMF 单模光纤 Single-mode FiberSMT 站点管理 Station ManagementSMTP 简单邮件传输协议 Simple Mail Transfer ProtocolSNA 系统网络体系结构 System Network ArchitectureSNMP 简单网络管理协议 Simple Network Management ProtocolSNR 信噪比 Signal-Noise ratioSONET 同步光纤网络 Synchronous Optical NetworkSTM 同步传输方式 Synchronous Transfer ModeSTP 屏蔽双绞线 Shielded Twisted PairSTS 同步传输信号 Synchronous Transport SignalSVC 交换虚电路 Switched Virtual CircuitSwitch 交换机TCP 传输控制协议 Transmission Control ProtocolTDM 时分多路复用 Time Division MultiplexingTFTP 单纯文件传输协议 Trivial File Transfer protocolTelnet 远程登录协议TIP 终端接口处理机 Terminal Interface ProcessorTP 双绞线 Twisted PairTSAP 传输层服务访问点 Transport Service Access PointUDP 用户数据报协议 User Datagram ProtocolUSB 通用串行总线 Universal Serial BusUTP 非屏蔽双绞线 Unshielded Twisted PairVAN 增值网 Value Added NetworkVBR 可变比特率 Variable Bit RateVCC 虚信道连接 Virtual Channel ConnectionVLAN 虚拟局域网 Virtual LANVLSI 超大规模集成电路VOD 点播图像 Video on DemandVPC 虚路径连接 Virtual Path ConnectionVPI 虚路径标识 virtual path identifierVPN 虚拟专用网络 Virtual Private NetworkVRML 虚拟现实造型语言 Virtual Reality Modeling Language VTP 虚拟隧道协议WAN 广域网 Wide Area NetworkWDM 波分多路复用 Wavelength Division MultiplexingWWW 万维网 World Wide Web。
软件开发技术常用术语英中翻译
软件开发技术常用术语英中对照A.I. 人工智能A2A integration A2A整合abstract 抽象的abstract base class (ABC)抽象基类abstract class 抽象类abstraction 抽象、抽象物、抽象性access 存取、访问access function 访问函数access level访问级别account 账户action 动作activate 激活active 活动的actual parameter 实参adapter 适配器add-in 插件address 地址address space 地址空间address-of operator 取地址操作符ADL (argument-dependent lookup)ADO(ActiveX Data Object)ActiveX数据对象advanced 高级的aggregation 聚合、聚集algorithm 算法alias 别名align 排列、对齐allocate 分配、配置allocator分配器、配置器angle bracket 尖括号annotation 注解、评注API (Application Programming Interface) 应用(程序)编程接口app domain (application domain)应用域appearance 外观append 附加application 应用、应用程序application framework 应用程序框架Approximate String Matching 模糊匹配Arbitrary Precision Arithmetic 高精度计算architecture 架构、体系结构archive file 归档文件、存档文件argument引数(传给函式的值)。
参见parameterarray 数组arrow operator 箭头操作符ASP(Active Server Page)活动服务器页面 worker process 工作者进程assembly 装配件、配件assembly language 汇编语言assembly manifest 装配件清单assert(ion) 断言assign 赋值assignment 赋值、分配assignment operator 赋值操作符associated 相关的、相关联的associative container 关联式容器(对应sequential container) asynchronous 异步的atomic 原子的atomic operation 原子操作attribute 特性、属性audio 音频authentication service 验证服务authorization 授权B2B integration B2B整合、B2B集成(business-to-business integration) background 背景、后台(进程)backup 备份backup device备份设备backup file 备份文件backward compatible 向后兼容、向下兼容bandwidth 带宽Bandwidth Reduction 带宽压缩base class 基类base type 基类型batch 批处理BCL (base class library)基类库Bin Packing 装箱问题binary 二进制binary function 双参函数binary large object二进制大对象binary operator 二元操作符binary search 二分查找binary tree 二叉树binding 绑定bit 位bitmap 位图bitwise 按位…bitwise copy 为单元进行复制；位元逐一复制,按位拷bitwise operation 按位运算block 块、区块、语句块bookkeeping 簿记boolean 布林值(真假值，true或false)border 边框bounds checking 边界检查boxing 装箱、装箱转换brace (curly brace) 大括号、花括号bracket (square brakcet) 中括号、方括号breakpoint 断点browser applications 浏览器应用(程序)browser-accessible application 可经由浏览器访问的应用程序bug 臭虫build 编连(专指编译和连接built-in 内建、内置bus 总线business 业务、商务(看场合)business Logic 业务逻辑business rules 业务规则buttons 按钮by/through 通过byte 位元组(由8 bits组成)cache 高速缓存calendar 日历Calendrical Calculations 日期call 调用call operator 调用操作符call-level interface (CLI)调用级接口(CLI)callback 回调candidate key 候选键 (for database)cascading delete 级联删除 (for database)cascading update 级联更新 (for database)casting 转型、造型转换catalog 目录chain 链(function calls)character 字符character format 字符格式character set 字符集check box 复选框check button 复选按钮CHECK constraints CHECK约束 (for database)checkpoint 检查点 (for database)child class 子类CIL (common intermediate language)通用中间语言、通用中介语言class 类class declaration 类声明class definition 类定义class derivation list 类继承列表class factory 类厂class hierarchy 类层次结构class library 类库class loader 类装载器class template 类模板class template partial specializations 类模板部分特化class template specializations 类模板特化classification 分类clause 子句cleanup 清理、清除CLI (Common Language Infrastructure) 通用语言基础设施client 客户、客户端client application 客户端应用程序client area 客户区client cursor 客户端游标 (for database)client-server 客户机/服务器、客户端/服务器clipboard 剪贴板Clique 最大团clone 克隆CLS (common language specification) 通用语言规范code access security 代码访问安全code page 代码页COFF (Common Object File Format) 通用对象文件格式collection 集合COM (Component Object Model) 组件对象模型Combinatorial Problems 组合问题combo box 组合框command line 命令行comment 注释commit 提交 (for database)communication 通讯compatible 兼容compile time 编译期、编译时compiler 编译器component组件composite index 复合索引、组合索引 (for database) composite key 复合键、组合键 (for database)composition 复合、组合Computational Geometry 计算几何concept 概念concrete具体的concrete class 具体类concurrency 并发、并发机制configuration 配置、组态Connected Components 连通分支connection 连接 (for database)connection pooling 连接池console 控制台constant 常量Constrained and Unconstrained Optimization 最值问题constraint 约束 (for database)construct 构件、成分、概念、构造（for language）constructor (ctor) 构造函数、构造器container 容器containment包容context 环境、上下文control 控件Convex Hull 凸包cookie (不译)copy 拷贝CORBA 通用对象请求中介架构(Common Object Request Broker Architecture) cover 覆盖、涵盖create/creation 创建、生成crosstab query 交叉表查询 (for database)CRTP (curiously recurring template pattern)Cryptography 密码CTS (common type system)通用类型系统cube 多维数据集 (for database)cursor 光标cursor 游标 (for database)custom 定制、自定义data 数据data connection 数据连接 (for database)Data Control Language (DCL) 数据控制语言(DCL) (for database)Data Definition Language (DDL) 数据定义语言(DDL) (for database)data dictionary 数据字典 (for database)data dictionary view 数据字典视图 (for database)data file 数据文件 (for database)data integrity 数据完整性 (for database)data manipulation language (DML)数据操作语言(DML) (for database)data mart 数据集市 (for database)data member 数据成员、成员变量data pump 数据抽取 (for database)data scrubbing 数据清理 (for database)data source 数据源 (for database)data source 数据源 (for database)Data source name (DSN) 数据源名称(DSN) (for database)data structure数据结构Data Structures 基本数据结构data table 数据表 (for database)data warehouse 数据仓库 (for database)data-aware control数据感知控件 (for database)data-bound 数据绑定 (for database)database 数据库 (for database)database catalog 数据库目录 (for database)database diagram 数据关系图 (for database)database file 数据库文件 (for database)database object 数据库对象 (for database)database owner 数据库所有者 (for database)database project 数据库工程 (for database)database role 数据库角色 (for database)database schema 数据库模式、数据库架构 (for database)database script 数据库脚本 (for database)datagram 数据报文dataset 数据集 (for database)dataset 数据集 (for database)DBMS (database management system)数据库管理系统 (for database) DCOM (distributed COM)分布式COMdead lock 死锁 (for database)deallocate 归还debug 调试debugger 调试器decay 退化decision support 决策支持declaration 声明declarative referential integrity (DRI)声明引用完整性(DRI) (for database)deduction 推导default 缺省、默认值DEFAULT constraint默认约束 (for database)default database 默认数据库 (for database)default instance 默认实例 (for database)default result set 默认结果集 (for database)defer 推迟definition 定义delegate 委托Delegates 一般译法为”委托”，微软没有对这个术语进行正式解释或翻译。
数据库安全文献翻译
英文译文数据库安全Paul MorrisonAmericaPART 1“为什么要确保数据库服务安全呢？任何人都不能访问-这是一个非军事区的保护防火墙”，当我们被建议使用一个带有安全检查机制的装置时，这是通常的反应。
事实上，在防护一个组织的信息方面，数据库的安全是至高无上的，因为它可能会间接接触比我们意识到的更广泛的用户。
这是两篇研究数据库安全文章中的第一篇。
在这篇文章中我们将讨论一般数据库安全概念和和比较普遍的问题。
在下篇文章，我们将把焦点放在特定的Microsoft SQL和Oracle的安全关注上。
近来数据库安全已成为一个热门话题。
随着越来越多的人关注计算机安全，我们发现，防火墙和网络服务器比以前都更加安全化了（虽然这并不等于说现在不再有许多不安全的网络存在）。
因此，重点是加大对技术的考虑力度，譬如以更细腻的审查态度对待数据库。
◆一般安全意识在我们讨论有关数据库安全问题之前，确保底层操作系统和支撑技术的安全是审慎而且必要的。
如果一个vanilla操作系统无法为数据库提供一个稳妥可靠的安全基础，花费太多努力去确保数据库安全是不值得的。
当安装操作系统时，有许多好的文献资料可以参考。
经常遇到的一个普遍问题，就是作为网络服务器托管Internet(or Intranet)的同一服务器上数据库的应用。
虽然这可能节省的购买一个单独的服务器费用，但这严重影响了安全问题。
如果这是确定的，当数据库开放地连接到互联网这种情况被证实了。
最近的一个例子，我记得是一个Apache网络服务器系统服务组织在互联网上提供的，与Oracle 数据库在互联网上提供有关端口1521。
在调查这个问题时进一步被发现，访问该Oracle 服务器是没有服务器加以制止之类的保护措施的（包括缺乏密码）。
从互联网发展前景看，这个数据库是不被推崇的，但默认设置的使用以及粗糙的安全措施，使服务器更加脆弱。
上面提到的问题并不是严格地数据库问题，还可以被归类为构建机制和防火墙保护问题，但最终它确是数据库，这是毫不妥协的。
中英文文献翻译
Database introduction and ACCESS2000The database is the latest technology of data management, and the important branch of computer science. The database , as its name suggests, is the warehouse to preserve the data. The warehouse to store apparatus in computer only, and data to deposit according to sure forms。
The so-called database is refers to the long-term storage the data acquisition which in the computer, organized, may share。
In the database data according to the certain data model organization, the description, and the storage, has a smaller redundance, the higher data independence and the easy extension, and may altogether shine for each kind of user。
The effective management database, frequently has needed some database management systems (DBMS) is the user provides to database operation each kind of order, the tool and the method, including database establishment and recording input, revision, retrieval, demonstration, deletion and statistics。
schema翻译
schema翻译Schema（模式）是一种用于描述数据结构的概念工具，它可以用来定义数据库中的表、字段、关系和约束等。
Schema可以提供数据的组织结构以及数据之间的关联方式。
下面是一些常见的Schema用法和相应的中英文对照例句：1. 创建Schema:- SQL: CREATE SCHEMA schema_name;- 例句：创建一个名为"my_schema"的Schema。
- CREATE SCHEMA my_schema;2. 创建表：- SQL: CREATE TABLE schema_name.table_name (column1 datatype, column2 datatype, ...);- 例句：在Schema "my_schema"下创建一个名为"my_table"的表。
- CREATE TABLE my_schema.my_table (id INT, name VARCHAR(50));3. 创建外键约束：- SQL: ALTER TABLE schema_name.table_name ADD CONSTRAINT constraint_name FOREIGN KEY (column_name) REFERENCES referenced_table_name (referenced_column_name);- 例句：在表"orders"中，为"customer_id"列添加外键约束，引用"customers"表的"customer_id"列。
- ALTER TABLE my_schema.orders ADD CONSTRAINT fk_orders_customers FOREIGN KEY (customer_id) REFERENCES my_schema.customers (customer_id);4. 修改表结构：- SQL: ALTER TABLE schema_name.table_name MODIFY COLUMN column_name datatype;- 例句：在表"my_table"中，将"age"列的数据类型修改为INT。
数据库 外文翻译 外文文献 英文文献 数据库安全
Database Security“Why do I need to secure my database server? No one can access it —it’s in a DMZ protected by the firewall!” This is often the response when it is recommended that such devices are included within a security health check. In fact, database security is paramount in defending an organizations information, as it may be indirectly exposed to a wider audience than realized.This is the first of two articles that will examine database security. In this article we will discuss general database security concepts and common problems. In the next article we will focus on specific Microsoft SQL and Oracle security concerns.Database security has become a hot topic in recent times. With more and more people becoming increasingly concerned with computer security, we are finding that firewalls and Web servers are being secured more than ever(though this does not mean that there are not still a large number of insecure networks out there). As such, the focus is expanding to consider technologies such as databases with a more critical eye.◆Common sense securityBefore we discuss the issues relating to database security it is prudent to high- light the necessity to secure the underlying operating system and supporting technologies. It is not worth spending a lot of effort securing a database if a vanilla operating system is failing to provide a secure basis for the hardening of the data- base. There are a large number of excellent documents in the public domain detailing measures that should be employed when installing various operating systems.One common problem that is often encountered is the existence of a database on the same server as a web server hosting an Internet (or Intranet) facing application. Whilst this may save the cost of purchasing a separate server, it does seriously affect the security of the solution. Where this is identified, it is often the case that the database is openly connected to the Internet. One recent example I can recall is an Apache Web server serving an organizations Internet offering, with an Oracle database available on the Internet on port 1521. When investigating this issue further it was discovered that access to the Oracle server was not protected (including lack of passwords), which allowed the server to be stopped. The database was not required from an Internet facing perspective, but the use of default settings and careless security measures rendered the server vulnerable.The points mentioned above are not strictly database issues, and could be classified as architectural and firewall protection issues also, but ultimately it is the database that is compromised. Security considerations have to be made from all parts of a public facing net- work. You cannot rely on someone or something else within your organization protecting your database fr om exposur e.◆ Attack tools are now available for exploiting weaknesses in SQL and OracleI came across one interesting aspect of database security recently while carrying out a security review for a client. We were performing a test against an intranet application, which used a database back end (SQL) to store client details. The security review was proceeding well, with access controls being based on Windows authentication. Only authenticated Windows users were able to see data belonging to them. The application itself seemed to be handling input requests, rejecting all attempts to access the data- base directly.We then happened to come across a backup of the application in the office in which we were working. This media contained a backup of the SQL database, which we restored onto our laptop. All security controls which were in place originally were not restored with the database and we were able to browse the complete database, with no restrictions in place to protect the sensitive data. This may seem like a contrived way of compromising the security of the system, but does highlight an important point. It is often not the direct approach that is taken to attack a target, and ultimately the endpoint is the same; system compromise. A backup copy of the database may be stored on the server, and thus facilitates access to the data indirectly.There is a simple solution to the problem identified above. SQL 2000 can be configured to use password protection for backups. If the backup is created with password protection, this password must be used when restoring the password. This is an effective and uncomplicated method of stopping simple capture of backup data. It does however mean that the password must be remembered!◆Curr ent tr endsThere are a number of current trends in IT security, with a number of these being linked to database security.The focus on database security is now attracting the attention of the attackers. Attack tools are now available for exploiting weaknesses in SQL and Oracle. The emergence of these tools has raised the stakes and we have seen focused attacks against specific data- base ports on servers exposed to the Internet.One common theme running through the security industry is the focus on application security, and in particular bespoke Web applications. With he functionality of Web applications becoming more and more complex, it brings the potential for more security weaknesses in bespoke application code. In order to fulfill the functionality of applications, the backend data stores are commonly being used to format the content of Web pages. This requires more complex coding at the application end. With developers using different styles in code development, some of which are not as security conscious as other, this can be the source of exploitable errors.SQL injection is one such hot topic within the IT security industry at the moment. Discussions are now commonplace among technical security forums, with more and more ways and means of exploiting databases coming to light all the time. SQL injection is a misleading term, as the concept applies to other databases, including Oracle, DB2 and Sybase.◆ What is SQL Injection?SQL Injection is simply the method of communication with a database using code or commands sent via a method or application not intended by the developer. The most common form of this is found in Web applications. Any user input that is handled by the application is a common source of attack. One simple example of mishandling of user input is highlighted in Figure 1.Many of you will have seen this common error message when accessing web sites, and often indicates that the user input has not been correctly handled. On getting this type of error, an attacker will focus in with more specific input strings.Specific security-related coding techniques should be added to coding standard in use within your organization. The damage done by this type of vulnerability can be far reaching, though this depends on the level of privileges the application has in relation to the database.If the application is accessing data with full administrator type privileges, then maliciously run commands will also pick up this level of access, and system compromise is inevitable. Again this issue is analogous to operating system security principles, where programs should only be run with the minimum of permissions that is required. If normal user access is acceptable, then apply this restriction.Again the problem of SQL security is not totally a database issue. Specific database command or requests should not be allowed to pass through theapplication layer. This can be prevented by employing a “secure coding” approach.Again this is veering off-topic, but it is worth detailing a few basic steps that should be employed.The first step in securing any application should be the validation and control of user input. Strict typing should be used where possible to control specific data (e.g. if numeric data is expected), and where string based data is required, specific non alphanumeric characters should be prohibited where possible. Where this cannot be performed, consideration should be made to try and substitute characters (for example the use of single quotes, which are commonly used in SQL commands).Specific security-related coding techniques should be added to coding standard in use within your organization. If all developers are using the same baseline standards, with specific security measures, this will reduce the risk of SQL injection compromises.Another simple method that can be employed is to remove all procedures within the database that are not required. This restricts the extent that unwanted or superfluous aspects of the database could be maliciously used. This is analogous to removing unwanted services on an operating system, which is common security practice.◆ OverallIn conclusion, most of the points I have made above are common sense security concepts, and are not specific to databases. However all of these points DO apply to databases and if these basic security measures are employed, the security of your database will be greatly improved.The next article on database security will focus on specific SQL and Oracle security problems, with detailed examples and advice for DBAs and developers.There are a lot of similarities between database security and general IT security, with generic simple security steps and measures that can be (and should be) easily implemented to dramatically improve security. While these may seem like common sense, it is surprising how many times we have seen that common security measures are not implemented and so causea security exposure.◆User account and password securityOne of the basic first principals in IT security is “make su re you have a good password”. Within this statement I have assumed that a password is set in the first place, though this is often not the case.I touched on common sense security in my last article, but I think it is important to highlight this again. As with operating systems, the focus of attention within database account security is aimed at administrationaccounts. Within SQL this will be the SA account and within Oracle it may be the SYSDBA or ORACLE account.It is very common for SQL SA accounts to have a password of ‘SA’ or even worse a blank password, which is just as common. This password laziness breaks the most basic security principals, and should be stamped down on. Users would not be allowed to have a blank password on their own domain account, so why should valuable system resources such as databases be allowed to be left unprotected. For instance, a blank ‘SA’password will enable any user with client software (i.e. Microsoft query analyser or enterprise manager to ‘manage’ the SQL server and databases).With databases being used as the back end to Web applications, the lack of password control can result in a total compromise of sensitive information. With system level access to the database it is possible not only to execute queries into the database, create/modify/delete tables etc, but also to execute what are known as Stored Procedures.数据库安全“为什么要确保数据库服务安全呢？任何人都不能访问-这是一个非军事区的保护防火墙”，当我们被建议使用一个带有安全检查机制的装置时，这是通常的反应。
中英文文献翻译-信息系统开发和数据库开发
英文原文：Information System Development and Database DevelopmentIn many organizations, database development from the beginning of enterprise data modeling, data modeling enterprises determine the scope of the database and the general content. This step usually occurs in an organization's information system planning process, it aims to help organizations create an overall data description or explanation, and not the design of a specific database. A specific database for one or more information systems provide data and the corporate data model (which may involve a number of databases) described by the organization maintaining the scope of the data. Data modeling in the enterprise, you review of the current system, the need to support analysis of the nature of the business areas, the need for further description of the abstract data, and planning one or more database development project. Figure 1 shows Pine Valley furniture company's enterprise data model of a part.1.1 Information System ArchitectureAs shown in figure 1, senior data model is only general information system architecture (ISA) or a part of an organization's information system blueprint. In the information system planning, you can build an enterprise data model as a whole information system architecture part. According to Zachman (1987), Sowa and Zachman (1992) views of an information system architecture consists of the following six key components:Data (Figure 1 shows, but there are other methods that).Manipulation of data processing (of a data flow diagram can be used, with the object model methods, or other symbols that).Networks, which organizations and in organizations with its main transmission of data between business partners (it can connect through the network topology map and to demonstrate).People who deal with the implementation of data and information and is the source and receiver (in the process model for the data shows that the sender and the receiver). Implementation of the events and time points (they can use state transition diagram and other means.)The reasons for the incident and data processing rules (often in the form of text display, but there are also a number of charts for the planning tools such as decision tables).1.2 Information EngineeringInformation systems planners in accordance with the specific information system planning methods developed information system architecture. Information engineering is a popular and formal methods. Information engineering is a data-oriented creation and maintenance of the information system. Information engineering is because the data-oriented, so when you begin to understand how the database is defined by the logo and when information engineering a concise explanation is very helpful. Information Engineering follow top-down planning approach, in which specific information systems from a wide range of informationneeds in the understanding derived from (for example, we need about customers, products, suppliers, sales and processing of the data center), rather than merging many detailed information requested ( orders such as a screen or in accordance with the importation of geographical sales summary report). Top-down planning will enable developers to plan more comprehensive information system, consider system components provide an integrated approach to enhance the information system and the relationship between the business objectives of the understanding, deepen their understanding of information systems throughout the organization in understanding the impact.Information Engineering includes four steps: planning, analysis, design and implementation. The planning stage of project information generated information system architecture, including enterprise data model.1.3 Information System Planning Information systems planning objective is to enable IT organizations and the business strategy closely integrated, such integration for the information systems and technology to make the most of the investment interest is very important. As the table as a description, information engineering approach the planning stage include three steps, we in the follow-up of three sections they discussed.1. Critical factors determining the planning Planning is the key factor that organizational objectives, critical success factors and problem areas. These factors determine the purpose of the establishment of planning and environment planning and information systems linked to strategic business planning. Table 2 shows the Pine Valley furniture company's key planning a number of possible factors, these factors contribute to the information systems manager for the new information systems and databases clubs top priority to deal with the demand. For example, given the imprecise sales forecasts this problem areas, information systems managers in the organization may be stored in the database additional historical sales data, new market research data and new product test data.2. The planning organizations set targetsOrganizations planning targets defined scope of business, and business scope will limit the subsequent analysis and information systems may change places. Five key planning targets as follows:●organizational units in the various sectors.●organizations location of the place of business operations.●functions of the business support organizations handling mission of the relevant group. Unlike business organizations function modules, in fact a function can be assigned to various organizations modules (for example, product development function is the production and sale of the common responsibility of the Ministry).●types of entities managed by the organization on the people, places and things of the major types of data.●Information System data set processing software applications and support procedures.3. To set up a business modelA comprehensive business model including the functions of each enterprisefunctional decomposition model, the enterprise data model and the various planning matrix. Functional decomposition is the function of the organization for a more detailed decomposition process, the functional decomposition is to simplify the analysis of the issue, distracted and identify components and the use of the classical approach. Pine Valley furniture company in order to function in the functional decomposition example in figure 2 below. In dealing with business functions and support functions of the full set, multiple databases, is essential to a specific database therefore likely only to support functions (as shown in Figure 2) provide a subset of support. In order to reduce data redundancy and to make data more meaningful, has a complete, high-level business view is very helpful.The use of specific enterprise data model to describe the symbol. Apart from the graphical description of this type of entity, a complete enterprise data model should also include a description of each entity type description of business operations and a summary of that business rules. Business rules determine the validity of the data.An enterprise data model includes not only the types of entities, including the link between the data entities, as well as various other objects planning links. Showed that the linkage between planning targets a common form of matrix. Because of planning matrix need not be explicit modeling database can be clearly described business needs, planning matrix is an important function. Regular planning matrix derived from the operational rules, it will help social development activities that top priority will be sorting and development activities under the top-down view through an enterprise-wide approach for the development of these activities. There are many types of planning matrix is available, their commonalities are:●locations - features show business function in which the implementation of operational locations.●unit - functions which showed that business function or business unit responsible for implementation.●Information System - data entities to explain how each information system interact with each data entity (for example, whether or not each system in each entity have the data to create, retrieve, update and delete).●support functions - data in each functional entities in the data set for the acquisition, use, update and delete.●Information System - target indication for each information system to support business objectives.Figure 3 illustrate a possible functions - data entities matrix. Such a matrix can be used for a variety of purposes, including the following three objectives:1) identify gaps in the data entities to indicate the types of entities not use any function or functions which do not use any entity.2) found that the loss of each functional entities involved in the inspection staff through the matrix to identify any possible loss of the entity.3) The distinction between development activities if the priority to the top of a system development function for a high-priority (probably because it important organizational objectives related), then this area used by entities in the development of the database has a high priority. Hoffer, George and Valacich (2002) are theworks of the matrix on how to use the planning and completion of the Information EngineeringThe planning system more complete description.2 database development processBased on information engineering information systems planning database is a source of development projects. These new database development projects is usually in order to meet the strategic needs of organizations, such as improving customer support, improve product and inventory management, or a more accurate sales forecast. However, many more database development project is the bottom-up approach emerging, such as information system user needs specific information to complete their work, thus beginning a project request, and as other information systems experts found that organizations need to improve data management and begin new projects. Bottom-up even in the circumstances, to set up an enterprise data model is also necessary to understand the existing database can provide the necessary data, otherwise, the new database, data entities and attributes can be added to the current data resources to the organization. Both the strategic needs or operational information needs of each database development projects normally concentrated in a database. Some projects only concentrated in the database definition, design and implementation of a database, as a follow-up to the basis of the development of information systems. However, in most cases, the database and associated information processing function as a complete information systems development project was part of the development. 2.1 System Development Life CycleGuide management information system development projects is the traditional process of system development life cycle (SDLC). System development life cycle is an organization of the database designers and programmers information system composed of the Panel of Experts detailed description, development, maintenance and replacement of the entire information system steps. This process is because Waterfall than for every step into the adjacent the next step, that is, the information system is a specification developed by a piece of land, every piece of the output is under an input. However shown in the figure, these steps are not purely linear, each of the steps overlap in time (and thus can manage parallel steps), but when the need to reconsider previous decisions, but also to roll back some steps ahead. (And therefore water can be put back in the waterfall!)Figure 4 on the system development life cycle and the purpose of each stage of the product can be delivered concise notes. The system development life cycle including each stage and database development-related activities, therefore, the question of database management systems throughout the entire development process. In Figure 5 we repeat of the system development life cycle stage of the seven, and outlines the common database at each stage of development activities. Please note that the systems development life cycle stages and database development steps一一对应exists between the relationship between the concept of modeling data in both systems development life cycle stages between.Enterprise ModelingDatabase development process from the enterprise modeling (system developmentlife cycle stage of the project feasibility studies, and to choose a part), Organizations set the scope and general database content. Enterprise modeling in information systems planning and other activities, these activities determine which part of information systems need to change and strengthen the entire organization and outlines the scope of data. In this step, check the current database and information systems, development of the project as the main areas of the nature of the business, with a very general description of each term in the development of information systems when needed data. Each item only when it achieved the expected goals of organizations can be when the next step.Conceptual Data ModelingOne has already begun on the Information System project, the concept of data modeling phase of the information systems needs of all the data. It is divided into two stages. First, it began the project in the planning stage and the establishment of a plan similar to Figure 1. At the same time outlining the establishment of other documents to the existing database without considering the circumstances specific development projects in the scope of the required data. This category only includes high-level data (entities), and main contact. Then in the system development life-cycle analysis stage must have a management information system set the entire organization Details of the data model definition of all data attributes, listing all data types that all data inter-entity business linkages, defining description of the full data integrity rules. In the analysis phase, but also the concept of inspection data model (also called the concept behind the model) and the goal of information systems used to explain other aspects of the model of consistency categories, such as processing steps, rules and data processing time of timing. However, even if the concept is such detailed data model is only preliminary, because follow-up information system life cycle activities in the design of services, statements, display and inquiries may find that missing element or mistakes. Therefore, the concept of data often said that modeling is a top-down manner, its areas of operation from the general understanding of the driver, rather than the specific information processing activities by the driver.3. Logical Database Design Logical database design from two perspectives database development. First, the concept of data model transform into relational database theory based on the criteria that means - between. Then, as the design of information systems, every computer procedures (including procedures for the input and output format), database support services, statements, and inquiries revealed that a detailed examination. In this so-called Bottom-up analysis, accurate verification of the need to maintain the database and the data in each affairs, statements and so on the needs of those in the nature of the data.For each separate statements, services, and so on the analysis must take into account a specific, limited but complete database view. When statements, services, and other analysis might be necessary to change the concept of data model. Especially in large-scale projects, the different analytical systems development staff and the team can work independently in different procedures or in a centralized, the details of their work until all the logic design stage may be displayed. In these circumstances, logic database design stage must be the original concept of data model and user view theseindependent or merged into a comprehensive design. In logic design information systems also identify additional information processing needs of these new demands at this time must be integrated into the logic of earlier identified in the database design.Logical database design is based on the final step for the formation of good data specifications and determine the rules, the combination, the data after consultation specifications or converted into basic atomic element. Most of today's database, these rules from the relational database theory and the process known as standardization. This step is the result of management of these data have not cited any database management system for a complete description of the database map. Logical database design completed, we began to identify in detail the logic of the computer program and maintenance, the report contents of the database for inquiries.4. Physical database design and definitionPhysical database design and definition phase decisions computer memory (usually disk) database in the organization, definition of According to the library management system for physical structure, the procedures outlined processing services, produce the desired management information and decision support statements. The objective of this stage is to design an effective and safe management of all data-processing database, the physical database design to closely integrate the information systems of other physical aspects of the design, including procedures, computer hardware, operating systems and data communications networks.5. Database ImplementationThe database prepared by the realization stage, testing and installation procedures for handling databases. Designers can use the standard programming language (such as COBOL, C or Visual Basic), the dedicated database processing languages (such as SQL), or the process of the non-exclusive language programming in order to produce a statement of the fixed format, the result will be displayed, and may also include charts. In achieving stage, but also the completion of all the database files, training users for information systems (database) user setup program. The final step is to use existing sources of information (documents legacy applications and databases and now needs new data) loading data. Loading data is often the first step in data from existing files and databases to an intermediate format (such as binary or text files) and then to turn intermediate loading data to a new database. Finally, running databases and related applications for the actual user maintenance and retrieval of data. In operation, the regular backup database and the database when damaged or affected resume database.6. Database maintenance During the database in the progressive development of database maintenance. In this step, in order to meet changing business conditions, in order to correct the erroneous database design, database applications or processing speed increase, delete or change the structure of the database. When a procedure or failure of the computer database affect or damage the database may also be reconstruction. This step usually is the longest in the database development process step, as it continued to databases and related applications throughout the life cycle, the development of each database can be seen as a brief database development processand data modeling concepts arise, logical and physical database design and database to achieve dealing with the changes.信息系统开发和数据库开发在许多组织中，从企业数据建模开始的数据库开发，企业数据建模确定数据库的范围和一般内容。
中英文翻译
Getting PHP to Talk to MySQlNow that you’re comfortable using the MySQL client tools to manipulate data in the database, you can begin using PHP to display and modify data from the database. PHP has standard functions for working with the database.F irst, we’re going to discuss PHP’s built-in database functions. We’ll also show you how to use the The PHP Extension and Application Repository (PEAR) databasefunctions that provide the ability to use the same functions to access any supported database. This type of flexibility comes from a process called abstraction. In programming interfaces, abstraction simplifies a complex interaction. It works by removing any nonessential parts of the interaction, allowing you to concentrate on the important parts. PEAR’s DB classes are one such database interface abstraction. The information you need to log into a database is reduced to the bare minimum. This standard format allows you to interact with MySQL, as well as other databases using the same functions. Similarly, other MySQL-specific functions are replaced with generic ones that know how to talk to many databases. For example, theMySQL-specific connect function is:mysql_connect($db_host, $db_username, $db_password);versus PEAR’s DB connect function:$connection =DB::connect("mysql://$db_username:$db_password@$db_host/$db_database");The same basic information is present in both commands, but the PEAR function also specifies the type of databases to which to connect. You can connect to MySQL or othe r supported databases. We’ll discuss both connection methods in detail.In this chapter, you’ll learn how to connect to a MySQL server fromPHP, how to use PHP to access and retrieve stored data, and how to correctly display information to the user.1 The ProcessThe basic steps of performing a query, whether using the mysql command-line tool or PHP, are the same:• Connect to the database.• Select the database to use.• Build a SELECT statement.• Perform the query.• Display the results.We’ll w alk through each of these steps for both plain PHP and PEAR functions.2 ResourcesWhen connecting to a MySQL database, you will use two new resources. The first is the link identifier that holds all of the information necessary to connect to the database for an active connection. The other resource is the results resource. It contains all information required to retrieve results from an active database query’s result set. You’ll be creating and assigning both resources in this chapter.3 Querying the Database with PHP FunctionsIn this section, we introduce how to connect to a MySQL database with PHP. It’s quite simple, and we’ll begin shortly with examples, but we should talk briefly about what actually happens. When you try connecting to a MySQL database, the MySQL server authenticates you based on your username and password. PHP handles connecting to the database for you, and it allows you to start performing queries and gathering data immediately.As in Chapter 8, we’ll need the same pieces of information to connect to the database: • The IP address of the database server• The name of the database• The username• The passwordBefore moving on, make sure you can log into your database using the MySQL command-line client.4 Including Database Login DetailsYou’re going to create a file to hold the information for logging into MySQL. Storing this information in a file you include is recommended. If you change the database password, there is only one place that you need to change it, regardless of how many PHP files you have that access the database.You don’t have to worry about anyone directly viewing the file and getting your database login details. The file, if requested by itself, is processed as a PHP file and returns a blank page.5 Troubleshooting connection errorsOne error you may get is:Fatal error: Call to undefined functionmysql_connect( ) in C:\Program Files\ApacheSoftware Foundation\Apache2.2\htdocs\db_test.php on line 4This error occurs because PHP 5.x for Windows was downloaded, and MySQL support was not included by default. To fix this error, copy the php_mysql.dll file from the ext/ directory of the PHP ZIP file to C:\php, and then C:\WINDOWS\php.ini.Make sure there are two lines that are not commented out by a semicolon (;) at the beginning of the line like these:extension_dir = "c:/PHP/ext/"extension=php_mysql.dllThis will change the extension to include the directory to C:/php and include the MySQL extension, respectively. You can use the Search function of your text editorto check whether the lines are already there and just need to be uncommented, or whether they need to be added completely.You’ll need to restart Apache, and then MySQL support will be enabled.6 Selecting the DatabaseNow that you’re connected, the next step is to select which database to use with the mysql_select_db command. It takes two parameters: the database name and,optionally, the database connection. If you don’t specify the database connection, the default is the connection from the last mysql_connect:// Select the database$db_select=mysql_select_db($db_database);if (!$db_select){die ("Could not select the database: <br />". mysql_error( ));}Again, it’s good practice to check for an error and display it every tim e you access the database.Now that you’ve got a good database connection, you’re ready to execute your SQL query.7 Building the SQL SELECT QueryBuilding a SQL query is as easy as setting a variable to the string that is your SQL query. Of cours e, you’ll need to use a valid SQL query, or MySQL returns with an error when you execute the query. The variable name $query is used since the name reflects its purpose, but you can choose anything you’d like for a variable name. The SQL query in this example is SELECT * FROM books.8 Executing the QueryTo have the database execute the query, use the mysql_query function. It takes two parameters—the query and, optionally, the database link—and returns the result. Save a link to the results in a variable called, you guessed it, $result! This is also a good place to check the return code from mysql_query to make sure that there were no errors in the query string or the database connection by verifying that $result is not FALSE:When the database executes the query, all of the results forma result set. These results correspond to the rows that you saw upon doing a query using the mysql command-line client. To display them, you process each row, one at a time.9 Fetching and DisplayingUse mysql_fetch_row to get the rows from the result set. Its syntax is:array mysql_fetch_row ( resource $result);It takes the result you stored in $result fromthe query as a parameter. It returns one row at a time from the query until there are no more rows, and then it returns FALSE. Therefore, you do a loop on the result of mysql_fetch_row and define some code to display each row:The columns of the result row are stored in the array and can be accessed one at a time. The variable $result_row accesses the second attribute (as defined in the query’s column order or the column order of the table if SELECT * is used) in the result row.10 Fetch typesThis is not the only way to fetch the results. Using mysql_fetch_array, PHP can place the results into an array in one step. It takes a result as its first parameter, and the way to bind the results as an optional second parameter. If MYSQL_ASSOC is specified, the results are indexed in an array based on their column names in the query. If MYSQL_NUM is specified, then the number starting at zero accesses the results. The default value, MYSQL_BOTH, returns a result array with both types. Themysql_fetch_assoc is an alternative to supplying the MYSQL_ASSOC argument.11 Closing the ConnectionAs a rule of thumb, you always want to close a connection to a database when you’redone using it. Closing a database with mysql_close will tell PHP and MySQL that you no longer will be using the connection, and will free any resources and memory allocated to it:mysql_close($connection)12 InstallingPEAR uses a Package Manager that oversees which PEAR features you install.Whether you need to install the Package Manager depends on which version of PHP you installed. If you’re running PHP 4.3.0 or newer, it’s already installed. If you’rerunning PHP 5.0, PEAR has been split out into a separate package. The DBpackage that you’re interested in is optional but installed by default with the Package Manager. So if you have the Package Manager, you’re all set.通过PHP访问MySQL现在你已经可以熟练地使用MySQL客户端软件来操作数据库里的数据，我们也可以开始学习如何使用PHP来显示和修改数据库里的数据了。
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数据库概论
A database consists of a file or a set of files. The information in these files may be broken down into records, each of which consists of one or more fields. Fields are the basic units of data storage, and each field typically contains information pertaining to one aspect or attribute of the entity described by the database. Using keywords and various sorting commands, users can rapidly search, rearrange, group, and select the fields in many records to retrieve or create reports on particular aggregates of data.
一个数据库由一个文件或文件集合组成。
这些文件中的信息可分解成一个个记录，每个记录有一个或多个域。
域是数据存储的基本单位，每个域一般含有由数据库描述的属于实体的一个方面或一个特性的信息。
用户使用键盘和各种排序命令，能够快速查找、重排、分组并在查找的许多记录中选择相应的域，建立特定集上的报表。
Database records and files must be organized to allow retrieval of the information. Early systems were arranged sequentially (i.e., alphabetically, numerically, or chronologically); the development of direct-access storage devices made possible random access to data via indexes. Queries are the main way users retrieve database information. Typically, the user provides a string of characters, and the computer searches the database for a corresponding sequence and provides the source materials in which those characters appear. A user can request, for example, all records in which the content of the field for a pe rson’s last name is the word Smith.
数据库记录和文件的组织必须确保能对信息进行检索。
早期的系统是顺序组织的(如：字母顺序、数字顺序或时间顺序);直接访问存储设备的研制成功使得通过索引随机访问数据成为可能。
用户检索数据库信息的主要方法是query(查询)。
通常情况下，用户提供一个字符串，计算机在数据库中寻找相应的字符序列，并且给出字符串在何处出现。
比如，用户能够在所有记录中寻找所有last name域为Smith的记录。
In flat databases [2], records are organized according to a simple list of entities; many simple databases for personal computers are flat in structure. The records in hierarchical databases are organized in a treelike structure, with each level of records branching off into a set of smaller categories. Unlike hierarchical databases, which provide single links between sets of records at different levels, network databases create multiple linkages between sets by placing links, or pointers, to one set of records in another; the speed and versatility of network databases have led to their wide use in business.
在非结构化的数据库中，按照实体的一个简单列表组织记录;很多个人计算机的简易数据库是非结构的。
层次型数据库按树型组织记录，每一层的记录分解成更小的属性集。
层次型数据库在不同层的记录集之间提供一个单一链接，与此不同，网络型数据库在不同记录集之间提供多个链接，这是通过设置指向其它记录集的链或指针来实现的。
网络型数据库的速度及多样性使其在企业中得到广泛应用。
Relational databases are used where associations among files or records cannot be expressed by links; a simple flat list becomes one table, or “relation”, and multiple relations can be mathematically associated to yield desired information. Object-oriented databases store and manipulate more complex data structures, called “objects”, which are organized into hierarchical classes that may inherit properties from classes higher in the chain; this database structure is the most flexible and adaptable.
当文件或记录间的关系不能用链表达时，使用关系型数据库。
一个表或一个“关系”，就是一个简单的非结构列表。
多个关系可通过数学关系提供所需信息。
面向对象的数据库存储并处理更复杂的称为对象的数据结构，可组织成有层次的类，其中的每个类可以继承层次链中更高一级类的特性，这种数据库结构最灵活，最具适应性。