introduction to database management system
DESCRIPTION
lecture manual for database systemTRANSCRIPT
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.