文档介绍：Chapter 1: Introduction
Chapter 1: Introduction
Database-System Application
Purpose of Database Systems
View of Data
Database Languages
Relational Databases
Database Design
Object-based and semistructured databases
Data Storage and Querying
Transaction Management
Data Mining and Analysis
Database Architecture
Database Users and Administrators
History of Database Systems
Database-System Application
DBMS contains information about a particular enterprise
Collection of interrelated data
Set of programs to access the data
An environment that is both convenient and efficient to use
Database Applications:
Banking: all transactions
Airlines: reservations, schedules
Universities: registration, grades
Sales: customers, products, purchases
Online retailers: order tracking, customized mendations
Manufacturing: production, inventory, orders, supply chain
Human resources: employee records, salaries, tax deductions
Databases touch all aspects of our lives
Purpose of Database Systems
In the early days, database applications were built directly 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
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 (. account balance > 0) e “buried” in program code rather than being stated explicitly
Hard to add new constraints or change existing ones
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
Example: Transfer of funds from one account to another should plete or not happen at all
Concurrent access by multiple users
Concurrent accessed needed for performance
Uncontrolled concurrent accesses can lead to