上海交通大学：《数据库系统原理 The principle of Database System》教学资源_Chapter 1 Introduction

Chapter 1 Introduction

Chapter 1 Introduction

Contents The history of Database System Overview of a database Management System(DBMS) Three aspects of database-system studies

Contents „ The history of Database System „ Overview of a database Management System (DBMS) „ Three aspects of database-system studies

Introduction to Database Systems What is a Database System? Database (data metadata) Hardware (disks) Software (DBMS) People (users,database designers and database administrators DBA)

Introduction to Database Systems What is a Database System? „ Database (data , metadata) „ Hardware (disks) „ Software (DBMS) „ People (users, database designers and database administrators DBA)

The history of Database Systems Early database management systems evolved from file system Network DBMS,Hierarchical DBMS Relational database Systems (in 1970, Ted Codd proposed tables called relations as a view of data in database) Object-oriented database Web database and XML

The history of Database Systems „ Early database management systems evolved from file system „ Network DBMS, Hierarchical DBMS „ Relational database Systems (in 1970, Ted Codd proposed tables called relations as a view of data in database) „ Object-oriented database „ Web database and XML

Drawbacks of using file systems to store data Data redundancy and inconsistency Multiple file formats,duplication of information in different files Database Difficulty in accessing data systems Need to write a new program to carry out each new task provide solutions to Data isolation-multiple files and formats all these problems ■Integrity problems Integrity constraints (e.g.account balance 0)become part of program code,Hard to add new constraints or change existing ones ■ Concurrent access by multiple users ■ Security problem

„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 (e.g. account balance > 0) become part of program code, Hard to add new constraints or change existing ones „ Concurrent access by multiple users „ Security problem … Drawbacks of using file systems to store data Database systems provide solutions to all these problems