QL Transaction Control Language (TCL) – COMMIT and ROLLBACK Tutorial

SQL Transaction Control Language (TCL) – COMMIT and ROLLBACK

Transaction Control Language (TCL) in SQL is used to manage transactions in a database. A transaction is a sequence of operations performed as a single logical unit of work. TCL commands ensure data integrity and consistency.

1. COMMIT

Definition: Saves all the changes made by the current transaction permanently to the database.

Syntax:

COMMIT;

Example:

INSERT INTO Student (student_id, name, dept_id)
VALUES (101, 'John Doe', 1);

COMMIT;

The new student record is now permanently saved in the Student table.

2. ROLLBACK

Definition: Undoes all changes made by the current transaction, reverting the database to its previous state.

Syntax:

ROLLBACK;

Example:

UPDATE Student
SET dept_id = 2
WHERE student_id = 101;

ROLLBACK;

The update is undone and the student’s department remains unchanged.

Lab Practice Tasks

  1. Insert a few rows into the Student table and COMMIT them.
  2. Update a record and then use ROLLBACK to undo changes.
  3. Perform multiple operations in a transaction and test COMMIT vs ROLLBACK.

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