Overview of DML , DDL, TCL,DCL

The Four SQL Command Categories

• DDL (Data Definition Language): defines and modifies database structure — CREATE, ALTER, DROP, TRUNCATE, RENAME.
• DML (Data Manipulation Language): manipulates the actual data within tables — INSERT, UPDATE, DELETE, MERGE.
• TCL (Transaction Control Language): manages transactions — COMMIT, ROLLBACK, SAVEPOINT.
• DCL (Data Control Language): manages access and permissions — GRANT, REVOKE.

Why the Distinction Matters

Understanding which category a statement belongs to clarifies its effect: DDL changes structure and auto-commits in most databases, DML changes data and can typically be rolled back until committed, and TCL explicitly controls when those changes become permanent.