SEQUEL

SEQUEL is a structured English query language used for interacting with a Relational database. SEQUEL is also known as SQL .

SEQUEL has five sub-languages in it like-

1. DDL (Data Definition Language):

This Language is used to define the structure of objects under the database with 4 commands in it.

Command	Description
Create	Crates a new table, view, any object in database
Alter	Modifies the table, view, existing database object
Drop	Destroy or delete the entire table
Truncate	Deletes all the data present under the table

2. DML(Data Manipulation Language):

This deals with the data under database with 3 commands in it.

Command	Description
Insert	Insert data in to table
Update	Modify or update tab
Delete	Destroy or delete row or rows from a table

3. DQL(Data Query Language):

this deals with data also but for retrieving of the data with 1 command in it.

Command	Description
Select	Retrieve the data either from table or tables

4. DCL(Data Control Language):

This is used for managing the security of objects using which one can Grant or Revoke permissions with 3 commands in it.

Command	Description
Grant	Gives a privilege to user
Revoke	Take back granted privileges from user
Deny	Reject or refuse the privilege to user

5. TCL(Transaction Control Language):

This is used for transaction management with 3 commands in it.

Command	Description
Commit	Update the changes in database
Rollback	Revert the changes database
Save	Save the changes database

Transaction is a set of actions which tells all the actions should be performed successfully or none of the action should be performed.