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Database Systems: Understanding Entities, Relational Model, and Hierarchical Model, Study notes of Database Management Systems (DBMS)

An overview of database systems, focusing on entities, attributes, records, and the relational and hierarchical models. It covers the concepts of data independence, metadata, data encoding, data control and protection, and various data models. The text also discusses the advantages and disadvantages of hierarchical and network models.

Typology: Study notes

2010/2011

Uploaded on 08/29/2011

aditi
aditi 🇮🇳

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DATABASE
DATABASE
MGMNT
MGMNT
SYSTEM
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DATABASEDATABASE

MGMNT MGMNT

SYSTEM SYSTEM

KEYWORDSKEYWORDS

DATABASE DATABASE

ENTITY ENTITY

RELATIONSHIP RELATIONSHIP

ATTRIBUTES ATTRIBUTES

DATABASE MANAGEMENT SYSTEM DATABASE MANAGEMENT SYSTEM

Cont….Cont….

ENTITIES ATTRIBUTES ANDENTITIES ATTRIBUTES AND

ASSOCIATION ASSOCIATION

ENTITY ENTITY

•A THING OR OBJECT•A THING OR OBJECT

•A DISTINGUISHABLE OBJECT•A DISTINGUISHABLE OBJECT

ABOUT WHICH WE WANT TOABOUT WHICH WE WANT TO

COLLECT INFORMATIONCOLLECT INFORMATION

Cont….Cont….

ATTRIBUTESATTRIBUTES

•PROPERTY OF AN ENTITY•PROPERTY OF AN ENTITY

•INFORMATION THAT WE WANT TO•INFORMATION THAT WE WANT TO

COLLECT ABOUT AN ENTITYCOLLECT ABOUT AN ENTITY

Cont….Cont….

EMPLOYEE ID

EMPLOYEE NAME

EMPLOYEE ID

EMPLOYEE.NAME

EMPLOYEE ID

EMPLOYEE NAME

A) ONE TO ONEONE TO ONE

EMPLOYEE ID EMPLOYEE SALARY SALARY EMPLOYEE ID EMPLOYEE ID SALARY

B) ONE TO MANYONE TO MANY

(MANY TO ONE RLTN BTW EMPLOYEE ID & SALARY)

RELATIONSHIP AMONG ENTITIES RELATIONSHIP EXIST AMONG DIFF ENTITIES EVEN THOUGH RELATIONSHIP MAY INVOLVE MORE THAN TWO ENTITIES - WE WILL CONCENTRATE ON THE RELATIONSHIP BTW TWO ENTITIES

STUDENTS ENROL COURSE LMNT

ENTITY SETS RELATIONSHIP

BORROWER

BORROWER

CUSTOMER LOAN

CUSTOMER LOAN

ONE TO ONE

ONE TO MANY

REPORTS TO

EMPLOYEE

BINARY RELATIONSHIP INVOLVING SAME ENTITY

DATABASE SYSTEMDATABASE SYSTEM

ARCHITECTURE ARCHITECTURE

Overall System StructureOverall System Structure

DATADATA

AS COMPARED TO STORAGE DATA , AS COMPARED TO STORAGE DATA ,

DATABASE APPROACH HASDATABASE APPROACH HAS

INTEGRATED DATA INTEGRATED DATA

SHARED DATA SHARED DATA

HARDWAREHARDWARE

PCS PCS

MINI COMPUTERS MINI COMPUTERS

MAIN FRAMES MAIN FRAMES

SOFTWARESOFTWARE

DBMS SOFTWARE DBMS SOFTWARE

APPLICATION SOFTWARE( USING APPLICATION SOFTWARE( USING

DBMS)DBMS)