SQL Command Types

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


      Merge :  Can perform insert, update, or delete operations in a single statement using the MERGE statement

     INSERT :   Inserts data into a table

     UPDATE: Updates existing data into a table

     DELETE : Deletes all records from a table

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


   CREATE – Creates objects in the database

   ALTER – Alters objects of the database

   DROP – Deletes objects of the database

   TRUNCATE – Deletes all records from a table and resets table identity to initial value.

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.

      GRANT – Gives user’s access privileges to database

      REVOKE – Withdraws user’s access privileges to database given with the GRANT command

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


     COMMIT – Saves work done in transactions

     ROLLBACK – Restores database to original state since the last COMMIT command in transactions

     SAVE TRANSACTION – Sets a savepoint within a transaction


DQL - DQL is abbreviation of Data Query Language. It is used to Query a data from table.

    SELECT: Retrieves data from a table