DATABASEDATABASESYSTEMSSYSTEMS

DATABASEDATABASE

A filing system for holding data Contains a set of similar files

– Each file contains similar records• Each record contains various fields

EXAMPLEEXAMPLE

3 files in a school personnel database– Student File

• contains a record for each student

– Faculty File• contains a record for each instructor

– Staff File• contains a file for each staff member

EXAMPLE (cont.)EXAMPLE (cont.)

Each record would contain similar fields– name, address, age, phone number, SSN, etc.

Special fields for various files– Student - GPA, ID number– Faculty - pay grade, Office location– Staff - pay grade

Field types result of database design

RELATIONAL DATABASERELATIONAL DATABASE

Stores data in a large table Each row represents a record Each column represents a field If two tables have a common field, we can

build a relation between them and combine them for dynamic queries

RDB EXAMPLERDB EXAMPLE

Student Personal Information File Student Grade File Student Schedule File All related by Student ID Number

DATABASE SYSTEMSDATABASE SYSTEMS

Must be able to process records– create, modify, add, delete, insert

Must be able to answer queries– eg. “list all students from Ohio”

Should have other capabilities– arithmetic ops, sorting, merging

DISTRIBUTED DATABASESDISTRIBUTED DATABASES

A new concept Many computers can hold a portion of

database, or Each computer holds a replica of database Each has advantages and disadvantages

DBMSDBMS

Database Management System Database is a collection of information DBMS is set of utilities that lets user

manipulate and maintain database MS ACCESS is example of DBMS