Data Definition Language(DDL) :

Data Definition language is used for creating database structure or database schema.
There are many DDL commands in Sql.

1-Create : Create command is used to create database.

2-Alter : Alter Command is used  for altering  database or table structure.

3-Truncate : Truncate  command is used to delete all data from database table.It delete all data   with     blank space .

4-Comment: Comment command are used for add comments to data dictionary.

5-Rename: Rename command are used for rename object name.

Data Manipulation Language(DML) :

DML is used for insertion,deletion,updation and managing information or data  from the database schema or database objects.

There are lots of DML commands in sql :--


1-Insert : Using insert command we can insert data into database object or database table

2-Update :Using update command we can update existing  data into database object or database table

3-Delete : With the help of delete command we can delete data from the database object or table.

4-Select : Select   command is  used to retrieve data from the database objecte or table.

 What Is Database In Short?

1- Database is designed to offer a ,mechanism for storing ,managing & retrieving 
     information.

2-Database is a structured collection of data & records that is stored in tables.

3-Sql is stands for "Structured Query Language".

4-Sql is a non procedural language.

5-Sql statements are used to perform  many task such as Updation,Deletion,Insertion
     of  data  in the database.   

6.According to ANSI(American National Standard Institute) "Sql Is A Standard Language 
    for relational database
  
There are few main category of Sql Database

1- (DDL)Data Definition Language .
2-(DML)Manipulation Language  .
3-(DCL)Data Control Language  .
4-(TCL)Transact Control Language . 
5-(DQL)Data Query Language .