SQL | ORACLE 10G| Introduction to SQL| Sql Tutorial | Lesson-1 in Sql.

 SQL

STRUCTURE QUERY LANGUAGE

STRUCTURE - IT IS A SET OF RULE

QUERY -REQUEST

LANGUAGE - COMMUNICATE

DEFINE DATA:-

    DATA IS A RAW FACT WHICH DESCRIBES THE PROPERTIES OF AN OBJECT.

OBJECT:-

ANYTHING THAT HAS EXISTENCE.

EXAMPLE:-

Properties or Attributes :

DATABASE:-

    

    DATABASE IS A PLACE OR MEDIUM WHICH WE STORE THE DATA SYSTEMATIC AND 

ORGANIZED MANNER.

 THE BASIC OPERATION THAT CAN BE PERFORM ON A DATABASE ARE

1.CREATE/INSERT

2.READ/RETRIEVE

3.UPDATE/MODIFY

4.DELETE/DROP.

DBMS - DATABASE MANAGEMENT SYSTEM:-

    IT IS A SOFTWARE WHICH IS USED TO MAINTAIN  AND MANAGE THE DATABASE.

    

IMPORTANT FEATURES OF DBMS:-

1.SECURITY

2.AUTHORIZATION 

 IN DBMS WE HAVE TO STORE THE DATA IN THE FORM OF FILE.

 IN DBMS WE USING QL- QUERY LANGUAGE TO COMMUNICATE WITH DBMS.

DRAWBACKS OF DBMS:-

•     WASTAGE OF MEMORY
•     FETCH FILE IS SLOW                  

TO OVERCOME DBMS WE GOING TO USE RDBMS.

WHAT IS RDBMS?

RDBMS - RELATIONAL DATABASE MANAGEMENT SYSTEM

            IT IS A SOFTWARE WHICH FOLLOW RELATION MODEL TO MAINTAIN AND MANAGE THE DATABASE.

            IN RDBMS WE STORE THE DATA IN THE FORM OF TABLES.

            SQL IS USED TO COMMUNICATE WITH RDBMS.

RULES OF E.F.CODD:-

1.THE DATA STORED IN THE CELL MUST BE A SINGLE VALUE DATA.

2.IN RDBMS WE HAVE STORE EVERYTHING IN THE FORM OF TABLES INCLUDING 

META DATA.

3.ACCORDING TO E.F.CODD WE CAN STORE THE DATA IN MULTIPLE TABLE , IF 

NEEDED WE CAN ESTABLISH CONNECTION BETWEEN TWO TABLES USING 

KEY ATTRIBUTES.

4.WE CAN VALIDATE THE DATA ENTERED INTO THE TABLE IN TWO STEPS

A.BY ASSIGNING DATATYPES.

B. BY ASSIGNING CONSTRAINTS.