SQL Data Definition Language (DDL)

Data Definition Language (DDL) in SQL:

A Data Definition Language or Data Description Language (DDL) is used to define data structures, especially it defines database schema.

The Data Definition Language DDL part of SQL permits database tables to create or delete. It also defines indexes (keys), it specifies links between tables, and also DDL imposes constraints between tables.

The most important DDL statements in SQL are given bellow:

• CREATE DATABASE

               – The CREATE DATABASE Query is used to creates a new database

• ALTER DATABASE

               - The ALTER DATABASE Query modifies a database

• DROP DATABASE

               - The DROP DATABASE Query deletes a database

• CREATE TABLE

               - The CREATE TABLE Query is used to create a new table

• ALTER TABLE

               – The ALTER TABLE SQL Query modifies a table

• DROP TABLE

               - DROP TABLE deletes a table

• CREATE INDEX

               - CREATE INDEX creates an index (search key) for the data in the table

• DROP INDEX

               - DROP INDEX Query deletes an index

We will see more about each SQL Statements and how to use these statements in your SQL Query in following SQL sessions.

Previous Chapter - SQL Data Manipulation Language (DML)

Next Chapter - SQL CREATE DATABASE Statement

SHARE