SQL Data Control Language

tutorial and example
tutorial and example

Data Control Language decides to whom should (which user) permit access privileges.

GRANT and REVOKE are the commands of DCL.

GRANT: It gives privileges to user.

REVOKE: It takes back privileges from granted user.

Data Query Language

Data Query Language does not make any changes in database. Neither schema level nor data level.

SELECT is a command of DQL.

SELECT: Retrieves data /records from table.

Syntax:

SELECT Column_1, Column 2, …..

FROM  Table_name

[WHERE condition];

Example:

  1. Select Student_id , Student_name

From Student

Where Student_id=’10’;

  1. Select Student_id , Student_name

From Student;

Syntax:

SELECT *

FROM  Table_name

[WHERE condition];

Example:

Select  *

From  Student

where Student_id=’10’;

  • This query retrieves single record with all its attributes/columns.
  • ‘* ‘Indicates all the fields/attributes/columns in the table.
  • Where condition is specified for a particular record.

Syntax:

SELECT *

FROM  Table_name;

Example:

SELECT *

FROM STUDENT;

It will retrieve all records and all the columns from the table. Where condition is not specified to fetch a particular record.