(8-7-21)MYSQL BASICS

                       

ADVANTAGES OF DBMS(DATABASE MANAGEMENT SYSTEM)

(1) REDUCES DATA REDUNDANCY TO A LARGE EXTENT

(2)  CAN CONTROL DATA INCONSISTENCY TO A LARGE EXTENT

(3) FACILITATES SHARING OF DATA

(4) ENFORCE STANDARDS

(5) DATABASE CAN ENSURE DATA SECURITY

(6) ENSURE DATA INDEPENDENCE

#IMPORTANT TERMS:-

-> DATA CONSTRAINTS :

DATA CONSTRAINTS ARE SET OF RULES THAT DEFINE VALID DATA

EG:- PRIMARY CONSTRAINTS ARE-NOT NULL , PRIMARY KEY , UNIQUE , CHECK , DEFAULT , FOREIGN KEY .

-> QUERY : 

A QUERY IS A TYPE OF COMMAND THAT RETRIEVES DATA FROM A DATABASE STORED ON A SERVER.

EG:- SELECT QUERY ,  ACTION QUERY .

-> DATA MANIPULATION : 

DATA MANIPULATION IS THE RESULT OF ACTION QUERIES .

EG:- INSERT , UPDATE , DELETE .

# RELATIONAL DATABASE MODEL:

IN A RELATIONAL DATA MODEL, THE DATA IS ORGANISED INTO TABLES(ROWS AND COLUMNS).THESE TABLES ARE CALLED RELATIONS.A ROW IN A TABLE REPRESENTS A RELATIONSHIP AMONG A SET OF VALUES.

EG OF COMMON RELATIONAL DATABASE MANAGEMENT SYSTEM:-

MICROSOFT SQL SERVER , MYSQL , ORACLE DATABASE , IBM INFORMIX , IBM DB2 .