Introduction to Database Management J.G. Zheng June 22 nd 2005 DB Chapter 1

Overview What is database and why database? Functions and components of database systems Advantages and disadvantages to use database

Introduction Some database history Database is widely used for businesses, organizations and governments to manage data and information, as well as for personal use

Sample Business Data An example of order form

Application Centered Approach Past data depended on applications (programs) to define their meanings and structures For example: What does these piece of data mean? BV BV

Data File Approach (Figure 1.1 on page 3)

Data File Problems The data file approach is problematic dealing with large quantities of data Redundancy increases input and maintenance efforts wastes space and slows down processing may introduce inconsistencies to the data Not scalable concurrency issue Limited security Size limitations

Database Approach Database processing features the separation of data from programs (data independence, or self-described) It provides a centralized management of data Data sharing Data management

Database Systems Basic elements of a database system See figure 1.8, 1.9 on page 12, 13

Database A database is a self-describing structure that can store information about multiple types of entities (tables), attributes (columns), and relationships (Figure 1.4 on page 7)

Relational Database Based on relations Relation is a mathematical concept relation table Data are arranged in 2-dimensional tables (relations) in a relational database More in Chapter 2 …

Database Management System DBMS serves as a controller (gatekeeper) for database, managing and controlling database activities reading, updating and deleting data data backup and recovery creating and maintaining tables and other structures controlling concurrency and consistency providing security DBMS uses SQL as command language (chapter 3)

Applications/Programs Applications (programs) serve as intermediaries between users and DBMS, to help users perform information processing tasks Functions include: Providing an easy-to-use user interface (menu, form, report) Executing business logic/process (calculation, analysis) …

Organizational Database System

Popular Products Desktop database system / personal database Microsoft Access Organizational database systems 1 Oracle (Oracle, 39.8% ) DB2 (IBM, 31.3% ) SQL Server (Microsoft, 12.1%) MySQL Most popular database for the web 1 market share data are from IDC 2003 Report

Advantages of Database

Disadvantages of Database

Database Design Design is a process (chapter 4 and 5) Analysis (conceptual design) Data modeling using Entity Relationship Diagram (ER) Design (logical design) Transforming ER to relations (figures on page 8) Real worldERTables

Summary Database processing is a centralized way to manage data (data centered) Database processing has great advantages when dealing with large quantities of data Database system consists of user, application, DBMS and database

Good Resources A short database history Largest databases