Any RDBMS SQL Queries/commands can be divided into three major subgroups.
* DDL (Data Definition Language ) which deals with database schemas and descriptions of how the data should reside in the database, thus the language statements like CREATE TABLE / ALTER TABLE belong to DDL
* DML (Data Manipulation Language ) which deals with data manipulation, and therefore includes most common SQL statements such as SELECT, INSERT, etc.
* DCL (Data Control Language ) which includes commands such as GRANT, and mostly concerns with rights, permissions, privileges and other controls of the database system.
