What is SQL

SQL (pronouncing as 'sequel') means Structured Query Language. It is a programming language to manage data in a DBMS or RDBMS. SQL is the back bone of any modern RDBMS.

History

SQL developed by IBM in 1970. In 1986 ANSI standardized the SQL.

SQL Statements

SELECT - Uses to fetches and displaying the data in a structured manner.

INSERT -  Uses to store data into the database.

UPDATE - Update or modify the stored data.

DELETE -  Removing the stored data.     

SELECT statement is the most widely and frequently used one. 

To explain the above statements we need to define a table first. Assume tat

EMP table stores employee details like Empno, Name, Age,

Structure of EMP Table

Empno	Name	Age
10	Mark	26
20	Adam	30
30	Gary	33
40	Lisa	27

There are 4 records in EMP table.


SELECT statement

Example :-  select * from EMP;     

Explanation :- 

The above statement will fetch all records from a table called EMP.

 

INSERT statement

Example :-  insert into EMP values(50,‘Lo‘,33);     

Explanation :- 

The above statement will insert one records into EMP table.

UPDATE statement

Example :-  update EMP set name = ‘Lopez‘ where Empno = 50;  

Explanation :- 

The above statement will update name column in EMP table.

Delete statement

Example :-  delete from EMP where Empno = 50;  

Explanation :- 

The above statement will update name column in EMP table.

We will discuss each SQL statements in a very detail manner.