Oracle divides database command into six groups. The six command groups are:
1. Data definition language (DDL) commands. These commands create tables, create declarative constraints, create stored procedures, and create triggers. Most types of database objects (table, views, procedures, triggers, tablespace, users, and so on) have CREATE, ALTER, and DROP commands; in other words, there are many DDL commands.
2. Data manipulation language (DML) commands. Data manipulation language (DML) commands let users move data into and out of a database. DML commands include SELECT, INSERT, UPDATE, and DELETE.
3. Data control language (DLC) commands. Data control language are commands to control which users can access specific data (tables , views, and so on). Data control statements include the GRANT and REVOKE commands, which you sue to grant and revoke privileges, as well as the SET ROLE command, which enables or disables roles in your current session.
4. Transaction control commands. Transaction control commands are used to identify the start and stop point of a transaction, to rollback a transaction, and to define check and savepoints. Transaction control commands include COMMIT, ROLLBACK, and SAVEPOINT.
5. System control commands. These are database administrative commands.
6. Embedded SQL commands. These commands support embedded SQL within application third-generation language programs. This allows C programs to execute SQL statements and called stored procedures from within the high-level source code.
