数据库英文翻译

database
Database is in accordance with the data structure to organize, storage and management of data warehouse, which arises from fifty years ago, with the dating of information technology and the development of the market, especially since the 1990s, data management is no longer merely data storage and management, and transformed into user needs of the various data management way. The database has a variety of types, from the most simple storage have various data form to can be carried out mass data storage of large database systems are obtained in each aspect has extensive application.
The birth of data management
Database's history can be traced back to fifty years ago, when the data management is very simple. Through a lot of classification, comparison and form rendering machine running millions of punched CARDS for data processing, its operation results on paper printed or punched card made new. While the data management is punched card for all these physical storage and handling. However, 1 9 5 1 year Remington Rand corporation (Remington Rand Inc.) an enzyme called Univac I computer launched a a second can input hundreds of recording tape drives, which has caused data management revolution. 1956 IBM produce the first disk drives -- the RAMAC Model 305. This drives have 50 blanks, each blanks diameter is 2 feet, can store 5 MB of data. The biggest advantage is use disk can be randomly access data, and punched CARDS and tape can order access data.
Database system appears in the 1960s the bud. When computer began to 实用文档
widely used in data management, the sharing of data put forward more and more high demand. The traditional file system already cannot satisfy people's needs. Manage and share data can unify the database management system (DBMS) came into being. The data model is the core and foundation of database system, various DBMS software are based on a data model. So usually in accordance with the characteristics of the data model and the traditional database system into mesh database, the hierarchy database and relational database three types.
Structured query language (SQL)
commercial database systems require a query language that is more user friendly. In this chapter,we study SQL, themost influential commercially marketed query language, SQL. SQL uses a combination of relational-algebra and relational-calculus constructs.Although we refer to the SQL language as a “query language,” it can do much more than just query a database. It can define the structure of the data, modify data in the database, and specify security constraints.It is not our intention to provide a complete users’ guide for SQL.Rather,we present SQL’s fundamental constructs and concepts. Individual implementations of SQL may differ in details, or may support only a subset of the full language.
2.1 Background
IBM developed the original version of SQL at its San Jose Research Laboratory (now
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the Almaden Research Center). IBM implemented the language, originally called Sequel, as part of the System R project in the early 1970s. The Sequel language has
evolved since then, and its name has changed to SQL (Structured Query Language).
Many products now support the SQL language. SQL has clearly established itself as
the standard relational-database language.
In 1986, the American National Standards Institute (ANSI) and the International Organization for Standardization (ISO) published an SQL standard, called SQL-86.
IBM published its own corporate SQL standard, the Systems Application Architecture Database Interface (SAA-SQL) in 1987. ANSI published an extended standard for
SQL, SQL-89, in 1989. The next version of the standard was SQL-92 standard, and the most recent version is SQL:1999. The bibliographic notes provide references to these standards.
Chapter 4 SQL
In this chapter, we present a survey of SQL, based mainly on the widely implemented SQL-92 standard. The SQL:1999 standard is a superset of the SQL-92 standard;we cover some features of SQL:1999 in this chapter, and
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provide more detailed coverage in Chapter 9. Many database systems support some of the new constructs in SQL:1999, although currently no database system supports all the new constructs. You should also be aware that some database systems do not even support all the features of SQL-92, and that many databases provide nonstandard features that we do
not cover here.
The SQL language has several parts:
•Data-definition language (DDL). The SQL DDL provides commands for defining relation schemas, deleting relations, and modifying relation schemas.•Interactive data-manipulation language (DML). The SQL DML includes a query language based on both the relational algebra and the tuple relational calculus. It includes also commands to insert tuples into, delete tuples from,and modify tuples in the database.
•View definition.The SQL DDL includes commands for defining views.•Transaction control. SQL includes commands for specifying the beginning and ending of transactions.
•Embedded SQL and dynamic SQL. Embedded and dynamic SQL define how SQL statements can be embedded within general-purpose programming languages, such as C, C++, Java, PL/I, Cobol, Pascal, and Fortran.•Integrity.The SQL DDL includes commands for specifying integrity constraints that the data stored in the database must satisfy. Updates that violate integrity 实用文档
constraints are disallowed.
•Authorization.The SQL DDL includes commands for specifying access rights to relations and views.
In this chapter, we cover the DML and the basic DDL features of SQL.Wealso briefly outline embedded and dynamic SQL, including the ODBC and JDBC standards for interacting with a database from programs written in the C and Java languages.
SQL features supporting integrity and authorization are described in Chapter 6,while Chapter 9 outlines object-oriented extensions to SQL.
The enterprise that we use in the examples in this chapter, and later chapters, is a
banking enterprise with the following relation schemas:
Branch-schema = (branch-name, branch-city, assets)
Customer-schema = (customer-name, customer-street, customer-city)
Loan-schema = (loan-number, branch-name, amount)
Borrower-schema = (customer-name, loan-number)
Account-schema = (account-number, branch-name, balance)
Depositor-schema = (customer-name, account-number)
Note that in this chapter, as elsewhere in the text, we use hyphenated names for schema, relations, and attributes for ease of reading. In actual SQL systems,
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however,
hyphens are not valid parts of a name (they are treated as the minus operator).
A simple way of translating the names we use to valid SQL names is to replace all hy phens by the underscore symbol (“ ”). For example, we use branch name in place of
branch-name.
2.2 Basic Structure
A relational database consists of a collection of relations, each of which is assigned a unique name. Each relation has a structure similar to that presented in Chapter 3.SQL allows the use of null values to indicate that the value either is unknown or does not exist. It allows a user to specify which attributes cannot be assigned null values,as we shall discuss in Section 4.11.
The basic structure of an SQL expression consists of three clauses: select, from,and where.
•The select clause corresponds to the projection operation of the relational algebra. It is used to list the attributes desired in the result of a query.•The from clause corresponds to the Cartesian-product operation of the relational algebra. It lists the relations to be scanned in the evaluation of the expression.
•The where clause corresponds to the selection predicate of the relational algebra. It consists of a predicate involving attributes of the relations that
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appear in the from clause.
That the term select has different meaning in SQL than in the relational algebra is an unfortunate historical fact. We emphasize the different interpretations here to minimize potential confusion.
A typical SQL query has the form
select A1,A2,...,An
from r1,r2,...,rm
where P
Each Ai represents an attribute, and each ri arelation. P is a predicate. The query is
equivalent to the relational-algebra expression
ΠA1,A2,...,An(σP (r1 × r2 × ··· × rm))
If the where clause is omitted, the predicate P is true. However, unlike the result of a relational-algebra expression, the result of the SQL query may containmultiple copies of some tuples; we shall return to this issue in Section 4.2.8.
SQL forms the Cartesian product of the relations named in the from clause,performs a relational-algebra selection using the where clause predicate, and then projects the result onto the attributes of the select clause. In practice, SQL may convert the expression into an equivalent form that can be processed more efficiently.
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However, we shall defer concerns about efficiency to Chapters 13 and 14.
In 1974, IBM's Ray Boyce and Don Chamberlin will Codd relational database 12 rule mathematical definition with simple keyword grammar expression comes out, put forward the landmark Structured Query Language (SQL) Language. SQL language features include inquiry, manipulation, definition and control, is a comprehensive, general relational database language, and at the same time, a highly the process of language, only request users do not need pointed out how do pointed out. SQL integration achieved database of all life cycle operation. SQL database provides and relations interact with the method, it can work with standard programming language. The date of the produce, SQL language became the touchstone of inspection relational database, and SQL standard every variation of guiding the relational database product development direction. However, until the twentieth century, the mid 1970s to the theory of relation in commercial database Oracle and SQL used in DB2.
In 1986, the SQL as ANSI relational database language American standards, that same year announced the standard SQL text. Currently SQL standard has three versions. ANSIX3135 - is defined as the basic SQL Database Language - 89, "Enhancement" SQL. A ANS89] [, generally called SQL - 89. SQL - 89 defines the schema definition, data operation and the transaction. SQL - 89 and subsequent ANSIX3168-1989, "Language - Embedded SQL Database, constituted the first generation of SQL standard. ANSIX3135-1992 [ANS92] describes a enhancements of SQL, now called SQL - 92 standards. SQL - 92 including mode operation, dynamic creation and SQL statements dynamic 实用文档
executive, network environment support enhancement. Upon completion of SQL - 92 ANSI and ISO standard, they started SQL3 standards development cooperation. The main features SQL3 abstract data types support, for the new generation of object relational database provides standard.
The nature of database data
1. Data integrity: database is a unit or an application field of general data processing system, he storage is to belong to enterprise and business departments, organizations and individuals set of related data. Database data from a global view, he according to certain data model organization, description and storage. Based on the structure of data between natural relation, thus can provide all the necessary access route, and data no longer deal with a certain applications, but for total organization, with a whole structural features.
2. Data sharing: database data is for many users sharing their information and the establishment, got rid of the specific procedures restrictions and restraint. Different users can use the database according to their respective usage the data; Multiple users can also Shared database data resource, i.e., different users can also access database in the same data. Data sharing each user not only meets the requirements of information, but also meet the various users of information communication between the requirements.
Object-oriented database
Along with the development of information technology and the market, 实用文档
people found relational database system, while technology is mature, but its limitations is obvious: it can be a very good treatment of so-called "form of data", but of dominating the more and more complex appear helpless type of data. Since the 1990s, technology has been studying and seek new database system. But in what is the development direction of the new database system, industry once is quite confused. The influence of agitation by technology at the time, for quite some time, people put a lot of energy spent on research "object-oriented database system (object oriented database)" or simply as "OO database system". What is worth mentioning, the United States Stonebraker professor proposed object-oriented RDS theory once favored by industry. And in Stonebraker himself Informix spend big money was then appointed technology director always.
However, several years of development, spatio-temporal object-oriented relational database system product market development situation is not good. Theoretically perfect sex didn't bring market warm response. The main reason of success, the main design thought database products with new database system is an attempt to replace the existing database system. This for many has been using database system for years and accumulated the massive job data, especially big customer for customers, is unable to withstand the conversion between old and new data that huge workload and big spending. In addition, object-oriented RDS system makes query language extremely complex, so whether database development businessman or application customers depending on the complicated application technology to be a dangerous road.
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Basic structure
The basic structure of database, reflects the three levels of observation database of three different Angle.
(1) physical data layer.
It is the most lining, is database on physical storage equipment actually stored data collection. These data are raw data, the object, the user is processed by internal model describing the throne of handled the instructions of string, character and word.
(2) conceptual data layer.
It is a layer of database, is among the whole logic said. Database Points out the logic of each data definition and the logical connection between data collection of storage and record, is. It is related to the database all objects logical relationship, not their physical condition, is under the database administrator concept of database.
(3) logical data layer.
It is the user sees and use the database, says one or some specific users use collections of data, namely the logical record set.
Database different levels is the connection between conversion by mapping. Main features
(1) to implement the data sharing.
Data sharing contains all users can also access database data, including the 实用文档
user can use all sorts of ways to use the database through interfaces, and provide data sharing.
(2) reduce data redundancy.
Compared with the file system, because the database to achieve data sharing so as to avoid the user respective establish application documentation. Reduce a lot of repeating data, reduce the data redundancy, maintain the consistency of the data.
(3) data of independence.
Data independence including database database of logical structure and application independent, also including data physical structure change does not affect the data of the logical structure.
(4) data realize central control.
File management mode, data in a decentralized state, different user or same users in different treatment had no relation between the documents. Using the database of data can be concentrated control and management, and through the data model of data organization and said the relation between data. (5) the data consistency and maintainability, to ensure the safety and reliability of the data.
Mainly includes: (1) the safety control: to prevent data loss, error updating and excessive use; (2) the integrity control: ensure data accuracy, effectiveness and compatibility; (3) the concurrent control: make in the same time period to
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allow data realization muli-access, and can prevent users of abnormal interaction between; (4) fault finding and recovery: the database management system provides a set of method, can isolate faults and repair fault, thereby preventing data breaches
(6) fault recovery.
The database management system provides a set of method, can isolate faults and repair fault, thereby preventing data breaches. Database system can restore database system is running as soon as possible, is probably the fault occurred in the physical or logical error. For instance, in system caused by incorrect operation data error, etc.
Database classification
1. The MaiJie openPlant real-time database
Real-time database system is a new field in database theory expansion, in power, chemical, steel, metallurgy, papermaking, traffic control and securities finance and other fields has a very broad application prospect. It can provide enterprises with high speed, timely real-time data services, to the rapidly changing real-time data to carry on the long-term effective history storage, is a factory control layer (fieldbus, DCS, PLC, etc) and production management system of the connection between the bridge, also process simulation, advanced control, online optimization, fault diagnosis system data platform. OpenPlant real-time database system used in today's advanced technology and architecture, can realize safe, stable and field each control system of the 实用文档
interface, and collected data efficient data compression and China's long
history of storage, meanwhile, we also provide convenient client application and general data interface (API/DDE/ODBC/JDBC/OPC, etc.), make the enterprise management and decision makers can prompt, and comprehensive understanding of the current production situation, also can look back at past production conditions, the timely discovery and the problems existing in the production, improve equipment utilization rate, reduce production cost, the enhancement enterprise's core competitive ability.
2. IBM DB2
As the pioneer and relational database fields, IBM pilot in 1977 completed System R System prototype, 1980 began to provide integrated database server - System / 38, followed by SQL/DSforVSE and VM, and its initial version is closely related with SystemR research prototype. In 1983 forMVSV1 DB2 launch. This version of the objective is to provide the new plan promised simplicity, data don't correlation and user productivity. 1988 DB2 for MVS provides a powerful online transaction processing (OLTP) support, 1989 and 1993 respectively to remote work unit and distributed work unit realized distributed database support. Recently launched Universal Database 6.1 is DB2 Database model gm, is the first online function with multimedia relational Database management system, support includes a series of platform, Linux.
3. Oracle
Oracle predecessor called SDL Ellison and another by a benchwarmer in 1977
founded two programmers, they have developed their own fist product in the 实用文档
market, a large sale, 1979, Oracle company introduces the first commercial SQL relational database management system. Oracle corporation is the earliest development relational database, its product support and producers of the most widely operating system platform. Now Oracle relational database products market share a front-runner.
4. Informix
Informix founded in 1980, the purpose is for Unix operating system to provide professional such open relational database products. The company's name from Information and Informix is the combination of Unix. Informix first truly support SQL database products is the relationship between Informix SE (StandardEngine). InformixSE is at the time of the microcomputer Unix environment main database products. It is also the first to be transplanted into the commercial database products on Linux.
5. Sybase
Sybase company was founded in 1984, the company name "Sybase" from "the system" and "database" combination of meaning. One of the company's founder Bob Sybase Epstein is Ingres university edition (and System/R the same period the relational database model products) of main design personnel. The company's first a relational database products are launched in 1987 SQLServer1.0 Sybase may. Sybase are first proposed the structure of database system/Server thoughts, and took the lead in SQLServer Sybase realize.
6. SQL Server
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In 1987, Microsoft and IBM cooperative development complete OS / 2, IBM in
its sales OS / 2 ExtendedEdition system binding Manager, and 2Database OS/production line is still lack of database of Microsoft products. Therefore, Microsoft will Sybase, Sybase foreign-exchange signed cooperation agreements with the technical development, the use of Sybase based on OS / 2 platform relational database. In 1989, Microsoft released SQL Server version 1.0.
7. PostgreSQL
PostgreSQL is a characteristic very complete free software objects - relational database management system (ORDBMS), and many of its characteristic is many of today's commercial database predecessor. The earliest PostgreSQL Ingres project started in BSD the. The characteristics of PostgreSQL covering the SQL - 2 / SQL - 92 and SQL - 3. First, it includes can say to the world's most abundant data types of support; Second, at present PostgreSQL is the only support affairs, son query, multiple versions parallel control system, data integrity checking the only features such as a free software database management system.
8. MySQL
MySQL is a small relational database management system, developers for Sweden mySQL AB corporation. In January 2008, was 16 from takeover. Currently MySQL is widely used in the small and medium-sized websites on the Internet. Because of its small size, speed, overall has low cost, especially
open-source this one characteristic, many small and medium-sized web site, in 实用文档
order to reduce the overall cost of ownership website and selected MySQL as website database
9 in Access databases
American Microsoft company in 1994 launched microcomputer database management system. It has friendly interface, easy easy to use, development is simple, flexible, and other features, is the interface typical of the new generation of desktop database management system. Its main features below: (1) perfect management, various database objects of strong data organization, user management, safety inspection functions.
(2) strong data processing functions, in a group level of network environment, use Access development multi-user database management system have traditional XBASE (DBASE, FoxBASE collectively) database system can achieve client/Server (Cient/Server) structure and the corresponding database security mechanism, the Access has many advanced large database management system has the characteristics, such as transaction processing/error rollback ability, etc.
(3) can be easily generate various data object, using the data stored build forms and statements, visibility.
(4) as Office suite, and part of the integrated, realize seamless connection version.
(5) can use Web searching and release data, realization and Internet connection. Access mainly suitable for small and medium application system, or 实用文档
as a client/server system of the client database.
10. SQLite
The ACID is to comply with SQLite relational databases management system, it contained within a relatively small C library. It is ichardHipp D.R established public domain project. Not as common client/server architecture examples, with SQLite engine is not a process of communication independent process, but connected to the program become a major part of it. So the main communication protocol is within the programming language direct API calls. This in gross consumption, time delay and overall simplicity have positive role. The entire database (definition, table, indexing and data itself) are both in the host host stored in a single file. It is through the simple design of starting a business in the whole data files and complete lock.
11. FoxPro database
At first by American Fox 1988, 1992 Fox launched by Microsoft company, have introduced after the takeover FoxPro2.5, 2.6 and VisualFoxPro etc, its function and performance version has greatly improved. FoxPro2.5, 2.6 into DOS and Windows two versions, respectively in DOS and running Windows environment. FoxPro FoxBASE in function and performance than and have improved greatly, mainly introducing the window, button, list box and text box control such as to enhance the system development capabilities.
Common databases
1. MySQL is the most popular open source SQL database management 实用文档
system, the company develops by MySQL AB, issuing, and support. MySQL AB is founded by several MySQL developer a commercial company. It is a second-generation open-source company, combined with open source value orientation, method and successful business model.
Features:
MySql core program using fully multi-threaded programming. Threading is lightweight processes, it can be flexibly provides services for users, and the system resources. But many
MySql can run in different operating systems. Say simply, MySql can support Windows95/98 / NT / 2000 and UNIX, Linux and OS from various operating system platform.
MySql have a very flexible and safe access and password system. When a customer and MySql server connection between all the password, they transmit encrypted, and MySql support host authentication.
Support ODBC for Windows. MySql support all the ODBC 2.5 function and many other functions, like this may use Access connections MySql server, thus make the MySql applications are greatly extend.
MySql support large database. Although written in Php web page for it as long as can deposit hundreds of above record data is enough, but MySql can easily support millions of recorded database.
MySql have a very rapid and stable memory allocation system based on the thread, can continue to use face don't have to worry about its stability.
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The strong search function. MySql support inquires the ramp of the SELECT and statements all operators and function, and can be in the same query from different database table mixes, thus make inquires the become quicker and easier.
PHP provides strong support for MySql, provide a whole set of the PHP function to MySql MySql, carry on the omni-directional support.
2. Based on the server is SQLServer database can be used for medium and large capacity data applications, on the function management is much more ambitious than Access. In handling mass data efficiency, backstage development aspects of flexibility, scalability is strong. Because now database are using standard SQL language to database management, so if it is standard SQL language, both basically can generic. 92HeZu nets all rent space can be used both double Access database, while supporting the SQL Server. SQL Server and more extended stored procedure, can use the database size without limit restrictions.
Graphical user interface, make the system management and database management more intuitive and simple.
The real client/server architecture.
Rich programming interface tools for users to program designed to provide more choices.
SQL Server with Windows NT, using a fully integrated many functions, such as NT send and receive messages, management login security, etc. SQL Server can 实用文档
be a very good and Microsoft BackOffice product integration.
Has the very good flexibility, can span from running Windows 95/98 laptop to run Windows 2000 large multiprocessor and so on many kinds of platform use. Technical support to the Web, users can easily will database data released on to the Web page.
SQL Server provides the data warehouse function, this function only in Oracle and other more expensive DBMS is only found in.
3. Access is a desktop database, is suitable only for data quantity is little, in dealing with the application of a database of data and single visit is very good, the efficiency is high. But it's also visit the client can't more than four. The access database has certain limit, if the data reach 100M or so, is very easy to create the server iis feign death, or consume server memory to crash the server.
The future development trend
With the expansion of information management content, appeared to rich variety of data model (hierarchical model, meshy model, relation model, object-oriented model, half structural model and so on), the new technology also emerge in endlessly (data streams, Web data management, data mining, etc.). Now every few years, international senior database experts assembled, discusses database research status, problems and future needs the new technology focus attention. The past existing several similar reports include: 1989 The Future Directions inDBMS Laguna BeachParticipants true - DatabaseSystems: Achievements in 1990, Opportunities, 1995. Inmon W.H. 实用文档。