In SQL language, the COMMIT statement is used to permanently save changes made to the database since the last COMMIT or ROLLBACK statement was executed.
The syntax for the SQL COMMIT statement is as follows:
The COMMIT statement is used in conjunction with the transaction management commands, which allow you to group multiple database changes into a single transaction. The basic syntax for a transaction is:
START TRANSACTION; -- SQL statements that modify the database COMMIT;
When you issue the COMMIT statement, all the changes made within the transaction are saved to the database. If any errors occur during the transaction, you can issue a ROLLBACK statement to undo all the changes made since the transaction began.
Suppose you want to update the salary of an employee in a database. You can do this by starting a transaction, updating the salary, and then committing the changes to the database. The following example demonstrates this:
START TRANSACTION; UPDATE employees SET salary = 50000 WHERE employee_id = 1234; COMMIT;
This code updates the salary of the employee with ID 1234 to 50000, and then saves the change to the database using the COMMIT statement. If there are no errors, the update will be permanent. However, if an error occurs during the transaction, such as a syntax error or a constraint violation, the transaction will be rolled back to its initial state, and no changes will be made to the database.
In summary, the COMMIT statement is a critical part of transaction management in SQL. It allows you to save changes to the database and commit them permanently, while also providing a mechanism for rolling back changes in case of errors.