浙江大学数据库系统概念第一章,对应原版教材第五版

1.4
©Silberschatz, Korth and Sudarshan, Bo Zhou
Purpose of Database Systems (Cont.)
Drawbacks of using file systems (cont.)
Atomicity of updates Failures may leave database in an inconsistent state with partial updates carried out E.g. transfer of funds from one account to another should either complete or not happen at all
Use of database grew last four decades
Very few people interacted directly with database system, custom did not know the backend database, they got printed report, etc.
unauthorized access
DBMS is a software: Set of programs to access the data
Be able to manage databases. Provides an environment that is both convenient and efficient to use.
In the early days, database applications were built on top of file systems
Drawbacks of using file systems to store data:
Data redundancy and inconsistency Multiple file formats, duplication of information in different files
Database system Introducems? Purpose of Database Systems Data Abstraction Database Languages Database Users Database System Structure Application Architectures History of Database Systems
Large amount of information (data) Well organized: Definition and Manipulation Share among several users, avoid possible anomalous results Safety of the information stored, despite system crash or
Some customs access system via phone interface. Direct user access via Internet.
The purpose of the course is to understand the fundamental of Database System.
Difficulty in accessing data Need to write a new program to carry out each new task
Data isolation — multiple files and formats Integrity problems
Integrity constraints (e.g. account balance > 0) become part of program code
Hard to add new constraints or change existing ones
Database System Concepts
Database System Concepts
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©Silberschatz, Korth and Sudarshan, Bo Zhou
Database Applications
Database touch all aspects of our lives
Banking: all transactions Airlines: reservations, schedules Universities: registration, grades Sales: customers, products, purchases Manufacturing: production, inventory, orders, supply chain Human resources: employee records, salaries, tax deductions
Database System Concepts
1.1
©Silberschatz, Korth and Sudarshan, Bo Zhou
Database System
Database System
Database DBMS
Database : Collection of interrelated data (information about a particular enterprise)
How to use DBMS. (included) How DBMS works. ( A brief introduction )
Database System Concepts
1.3
©Silberschatz, Korth and Sudarshan, Bo Zhou
Purpose of Database Systems