SQL Commands – DDL, DML, DCL, TCL.

SQL commands are categorized into four types:

1. DDL (Data Definition Language):
   • Defines and modifies database structure.
   • Commands: CREATE, ALTER, DROP, TRUNCATE.
   • Example: CREATE TABLE students (id INT, name VARCHAR(50));
2. DML (Data Manipulation Language):
   • Handles data manipulation within tables.
   • Commands: INSERT, UPDATE, DELETE, SELECT.
   • Example: INSERT INTO students VALUES (1, 'John');
3. DCL (Data Control Language):
   • Manages access permissions.
   • Commands: GRANT, REVOKE.
   • Example: GRANT SELECT ON students TO user1;
4. TCL (Transaction Control Language):
   • Controls transactions.
   • Commands: COMMIT, ROLLBACK, SAVEPOINT.
   • Example: COMMIT;