Introduction to Databases Chapter 1 Introduction to Databases Thomas Connolly, Carolyn Begg, Database System, A Practical Approach to Design Implementation and Management, 4th Edition, Addison Wesley Pg 3 ~ 26

Learning Outcomes Introduction Traditional File-based Systems Database Approach Roles in the Database Environment Advantages & Disadvantages of DBMS

Examples of Database Application Purchases from the supermarket Purchases using credit card Booking a holiday at the travel Using the local library Taking out insurance Using the Internet Studying at university

File-based Definition Collection of application program that perform services for the end users (e.g reports) Program defines and manages it’s own data

File-based Processing

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

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

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

Database Management System (DBMS)

DBMS Environment Hardware Software Data People Procedure 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

Roles in the Database Environment Data Administrator (DA) Management of data resources Ensure database development support corporate objectives Database Administrator (DBA) Physical realization of database More technically oriented Database Designers Logical Identifying data Physical Realization of logical database Application Programmers Implement application program for user End Users (Naïve and Sophisticated)

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