Data Definition Language(DDL)
This is used to specify the Database Schema, tables, etc. The basic structure of the database can be set using DDL. The output of DDL is called the “Data Dictionary”. The Data Dictionary contains the MetaData.
The operations that can be performed on DDL are:
Alter: The database structure can be modified.
Create: Creates objects in the database.
Drop: Deletes objects in the database.
Truncate: Remove all items from the relation.
Rename: Helps to rename an object.
Comment: Comments on an object in a dictionary.
Data Manipulation Language(DML)
DML helps to manipulate and access data from the database. The user commands are handled by DML.
Some of the commands that DML can perform are:
Select: Accesses data from the database.
Insert: Inserts data into a table.
Update: Updates existing data in a table.
Delete: Deletes all data from a table.
Merge: Performs UPSERT operation(insertion or update).
Call: Calls a structured query or sublanguage.
Data Controlled Language(DCL)
The DCL command helps to retrieve the previously stored data from the database.
Commands that DCL can perform are:
Grant: Gives user access permissions to the database.
Revoke: Removes permissions to the database from the user.