SQL:Components

Overview
SQL consists of these component languages:

Data Definition Language (DDL)
The Data Definition Language (DDL) is used to create and delete databases and tables. The following SQL Commands are available;


 * CREATE DATABASE creates a new database.
 * DROP DATABASE removes a database and any tables it contains.
 * CREATE TABLE creates a new table.
 * DROP TABLE removes a table and any data it contains.
 * ALTER TABLE modifies the structure of an existing table.
 * CREATE INDEX adds an index to a table.
 * DROP INDEX removes an index from a table.

Data Manipulation Language (DML)
The Data Manipulation Language (DML) is used to change, add and delete data in an existing table. The following SQL Commands are available:
 * INSERT
 * UPDATE
 * DELETE

Data Query Language (DQL)
The Data Query Language (DQL)is used to display the data in a table or tables. The following SQL Commands are available:
 * SELECT

SQL always produces a SET of data, which is basically a rectangular block of rows (records) and columns (fields). The data set produced is always a single table.

Data ControlLanguage (DCL)

 * Grant
 * Revoke

Transaction Processing Language (TPL)

 * Begin work
 * Rollback
 * Commit