Transaction Control Statements

Transaction control statements manage the changes made by DML statements and group DML statements into transactions. They enable you to:

Make a transaction's changes permanent (COMMIT)
Undo the changes in a transaction, either since the transaction started or since a savepoint (ROLLBACK)

This topic includes the following topics:

Committing Transaction Changes
Rolling Back a Transaction

Committing Transaction Changes

The SQL COMMIT statement saves any changes you have made to the database. When a COMMIT has been executed, all the recent changes since the last COMMIT, or since you logged on as the current user, are saved.

Example: Using the COMMIT Statement shows how to use COMMIT to commit (save) changes to the employees table in the database.

Using the COMMIT Statement

-- add a row and then update the data
INSERT INTO employees (employee_id, last_name, email, hire_date, job_id, salary)
  VALUES (301, 'Doe', 'john.doe', '31-AUG-05', 'SH_CLERK', 2400); 

UPDATE employees SET salary = salary*1.10 WHERE employee_id = 301;

-- commit (save) the INSERT and UPDATE changes in the database
COMMIT;

Rolling Back a Transaction

You can use the SQL ROLLBACK statement to rollback (undo) any changes you made to the database before a COMMIT has been executed.

Example: Using the ROLLBACK Statement shows how to use ROLLBACK to rollback the deletions made to the employees table. Note that the ROLLBACK was issued before a COMMIT was executed.

Using the ROLLBACK Statement

-- delete a row (record)
DELETE FROM employees WHERE last_name = 'Doe';

-- rollback the delete statement because the previous DELETE was incorrect
ROLLBACK;

-- the following is valid
SELECT * FROM employees WHERE last_name = 'Doe';