INTRODUCTION TO DATABASE MANAGEMENT SYSTEM

Definitions and Terms

Database An organized collection of logically

related data Data

Stored representations of objects and events that have meaning and importance in the user’s environment

Definitions and Terms

Types of Data Structured data▪ Facts concerning objects and events that

could be recorded and stored on computer media

Unstructured data▪ Multimedia data (documents, maps,

photographic images, sound and video segments)

Definitions and Terms

Information Data that have been processed in such a

way as to increase the knowledge of the person who uses the data

Metadata Data that describe the properties or

characteristics of end user data Database Management System

A software system that is used to create, maintain, and provide controlled access to user databases

Components of the Database Environment

Computer-Aided Software Engineering (CASE) tools Automated tools used to designed databases

and application programs Repository

A centralized knowledge base of all data definitions, data relationships, screen and report formats, and other system components

DBMS A software system that is used to create,

maintain, and provide controlled access to user database

Components of the Database Environment

Database Application Program

Computer programs that are used to create and maintain the database and provide information to users.

User Interface Languages, menus, and other facilities by which

users interact with various system components Data and database administrators

Persons who are responsible for the overall management of data resources in an organization.

Components of the Database

CASE tools

User Interface

Application

Programs

DBMSRepository

Database

Modeling Data in the Organization

The E-R Model

Entity-relationship model (E-R model) A detailed, logical representation of the

data for an organization or for a business area

It is expressed in terms of entities in the business environment, the relationships (or associations) among those entities, and the attributes (or properties) of both the entities and their relationships.

Entity-relationship diagram Graphical representation of an E-R diagram

The E-R Model NotationBasic

Symbols

EntityRelationship

Attribute

Relationship degree

UnaryBinary

Ternary

Entity-Relationship Model Constructs

Entity A person, place, object, event, or concept

in the user environment about which the organization wishes to maintain data▪ Person: EMPLOYEE, STUDENT, PATIENT▪ Place: STORE, WAREHOUSE, STATE▪ Event: SALE, REGISTRATION,

RENEWAL▪ Concept: ACCOUNT, COURSE, WORK CENTER

Entity-Relationship Model Constructs

Entity Type A collection of entities that share

common properties of characteristics Entity Instance

A single occurrence of an entity type

Entity-Relationship Model Constructs

Rules in Naming Entity Types An entity type name is singular noun. An entity type name should be specific to the organization

▪ CUSTOMER, CLIENT▪ PURCHASE ORDER, CUSTOMER ORDER

An entity type name should be concise, using few words as possible.▪ REGISTRATION instead of STUDENT REGISTRATION FOR CLASS

An abbreviation or short name should be specified for each entity type name, and the abbreviation may be sufficient to use in the E-R diagram.

Event entity types should be named for the result of the event, not the activity or process of the event.

The name used for the same entity type should be the same on all E-R diagrams on which the entity type appears.