Chapter 1 Introduction to Databases

Chapter 1 Introduction to Databases

Agenda File-based Systems History of Database Database Management Systems (DBMS)

File-based Definition Program defines and manages it’s own data

Limitations of File-based Separation and isolation Duplication Program & data dependence Fixed queries Proliferation of application programs

History of Database Systems First generation – Hierarchical model Information Management System (IMS) – Network model Conference on Data System Languages (CODASYL) Data Base Task Group (DBTG) – Limitation Complex program for simple query Minimum data independence No theoretical foundation Second generation – Relational model E. R. Codd DB2, Oracle – Limitation Limited data modeling Third generation – Object-relational DBMS – Object-oriented DBMS

Database Definition – A collection of self-describing and integrated data files System catalog – Meta data – Data dictionary – Overhead data Data abstraction

Database Management System Facility Data definition language (DDL) Data manipulation language (DML) Structured query language (SQL) Security system Integrity system Concurrency control system Backup & recovery system View mechanism

DBMS Environment Hardware – Client-server architecture Software – dbms, os, network, application Data – Schema, subschema, table, attribute People – – – – Data administrator & database administrator Database designer: logical & physical Application programmer End-user: naive & sophisticated Procedure – Start, stop, log on, log off, back up, recovery

Advantages of DBMS Control redundancy Consistency Integrity Security Concurrency control Backup & recovery Data standard More information Data sharing & conflict control Productivity & accessibility Economy of scale Maintenance

Limitations of DBMS Complexity Size Cost – Software – Hardware – Conversion Performance Vulnerability

Points to Remember File-based Systems History of Database Database Management Systems (DBMS)

Assignment Review Chapter 1 Read appendix C Turn in your group list: (due 9/18/07) before class starts (1 point for on time roster, 0 for late one)