DATABASE SYSTEMS

DATABASE u A filing system for holding data u Contains a set of similar files –Each file contains similar records Each record contains various fields

EXAMPLE u 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.) u Each record would contain similar fields –name, address, age, phone number, SSN, etc. u Special fields for various files –Student - GPA, ID number –Faculty - pay grade, Office location –Staff - pay grade u Field types result of database design

RELATIONAL DATABASE u Stores data in a large table u Each row represents a record u Each column represents a field u If two tables have a common field, we can build a relation between them and combine them for dynamic queries

RDB EXAMPLE u Student Personal Information File u Student Grade File u Student Schedule File u All related by Student ID Number

DATABASE SYSTEMS u Must be able to process records –create, modify, add, delete, insert u Must be able to answer queries –eg. “list all students from Ohio” u Should have other capabilities –arithmetic ops, sorting, merging

DISTRIBUTED DATABASES u A new concept u Many computers can hold a portion of database, or u Each computer holds a replica of database u Each has advantages and disadvantages

DBMS u Database Management System u Database is a collection of information u DBMS is set of utilities that lets user manipulate and maintain database u MS ACCESS is example of DBMS