Saturday, May 28, 2011

DML, DDL, DCL, TCL in SQL Server


Different Types of Sql Statements:-

DML
DML is abbreviation of Data Manipulation Language. It is used to retrieve, store, modify, delete, insert and update data in database.

Examples: SELECT, UPDATE, INSERT statements

Select :- This Sql Statement is used to extract the data from one or combination of tables
Update:- This Sql Statement is used to update the data in a database table.
Delete:- This Sql Statement is used to delete data from the database table.
Insert Into :- This Sql Statement is used to insert data into a database(table)

DDL
DDL is abbreviation of Data Definition Language. It is used to create and modify the structure of database objects in database.

Examples: CREATE, ALTER, DROP statements

Create Table:- This Sql Statements is used to create a Table
Alter Table:- This Sql Statement is used to Alter the table definition like adding any columns or deleting any table column.
Drop table:- This Sql Statement is used to Drop the table.
Create Index:- This Sql Statement is used to Create a Index on a table
Drop Index:- This Sql Statement is used to drop a table from the table

DCL

DCL is abbreviation of Data Control Language. It is used to create roles, permissions, and referential integrity as well it is used to control access to database by securing it.

Examples: GRANT, REVOKE statements
Grant :- This Sql Statement is used to give access rights to the user for the database
Revoke:- This Sql Statement is used to revoke or delete the access rights of some of the users for a given database.

TCL

TCL is abbreviation of Transactional Control Language. It is used to manage different transactions occurring within a database.

Examples: COMMIT, ROLLBACK statements

Commit:- This command is used to save the work done by the user.
Rollback:-  This command is used to delete the data till the last committed state of the database.

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