CHAPTER 12 : DATABASE

WHAT IS DATA?

• DATA CAN BE DEFINED AS FACTS OR OBSERVATIONS ABOUT PEOPLE,PLACES,THINGS, AND EVENTS
• NOT LONG AGO,DATA LIMITED TO NUMBERS,LETTERS AND SYMBOLS RECORDED BY KEYBOARDS. NOW DATA ALSO INCLUDES AUDIO,MUSIC,PHOTOGRAPH AND VIDEO

2 WAYS TO VIEW DATA
PHYSICAL VIEW - FOCUSES ON THE ACTUAL FORMAT AND LOCATION OF THE DATA
LOGICAL VIEW - FOCUSES ON THE MEANING,CONTENT AND CONTEXT OF THE DATA

NEED FOR DATABASES

DATABASE MANAGEMENT

• CREATE, MODIFY AND GAIN ACCESS TO A DATABASE
• COMMONLY ABBREVIATED DBMS
• DBMS SOFTWARE IS MADE UP OF 5 PARTS OR SUBSYSTEMS WHICH IS DBMS ENGINE,DATA DEFINITION,DATA MANIPULATION,APPLICATION GENERATION AND DATA ADMINISTRATION.

DBMS STRUCTURE

•  DBMS PROGRAMS ARE DESIGNED TO WORK WITH DATA TAHT IS LOGICALLY STRUCTURED OR ARRANGED
• DATA MODEL DEFINE RULES AND STANDARDS FOR DATA IN DATABASE
• 5 COMMON DATA MODEL INCLUDES :

  NETWORK DATABASE

  HIERARCHICAL DATABASE

OBJECT-ORIENTED DATABASE

• RELATIONAL DATABASE

• MULTIDIMENSIONAL DATABASE 

 TYPES OF DATABASES
DATABASES MAY BE CLASSIFIED INTO 4 TYPES :

1. INDIVIDUAL DATABASE

• ALSO CALLED A MICROCOMPUTER DATABASE
• IT IS A COLLECTION OF INTEGRATED FILES PRIMARILY USED BY JUST ONE PERSON. 

2.  COMPANY OR SHARED DATABASES

•  USUALLY STORED ON A CENTRAL DATABASE SERVER AND MANAGED BY A DATABASE ADMINISTRATOR

     3.  DISTRIBUTED DATABASES

• DATABASE IS LOCATED IN A PLACE OR PLACES OTHER THAN WHERE USERS ARE LOCATED

     4.  COMMERCIAL DATABASES

• IS GENERALLY AN ENORMOUS DATABASE THAT AN ORGANIZATION DEVELOPS TO COVER PARTICULAR SUBJECTS.