What are the difference between DDL, DML and DCL commands?

What are the difference between DDL, DML and DCL commands?

SQL can be divided into two parts: 
> The Data Manipulation Language (DML)
> The Data Definition Language (DDL).
The query and update commands form the DML part of SQL:
> SELECT - extracts data from a database
> UPDATE - updates data in a database
> DELETE - deletes data from a database
> INSERT INTO - inserts new data into a database
The DDL part of SQL permits database tables to be created or deleted. It also define indexes (keys), specify links between tables, and impose constraints between tables. The most important DDL statements in SQL are:
> CREATE DATABASE - creates a new database
> ALTER DATABASE - modifies a database
> CREATE TABLE - creates a new table
> ALTER TABLE - modifies a table
> DROP TABLE - deletes a table
> CREATE INDEX - creates an index (search key)
> DROP INDEX - deletes an index
Data Control Language (DCL) statements. Some examples:
> GRANT - gives user\'s access privileges to database
> REVOKE - withdraw access privileges given with the GRANT command

Date:2009-01-09 00:00:00

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