Auto-commit behavior in SQL - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is auto-commit behavior in SQL databases?

Auto-commit behavior means that every SQL statement is treated as a complete transaction and is automatically saved (committed) to the database without needing an explicit commit command.

beginner

How does auto-commit affect data changes in a database?

With auto-commit on, each change is immediately saved and visible to others. If auto-commit is off, changes stay temporary until you explicitly commit them.

intermediate

How can you turn off auto-commit in SQL?

You can turn off auto-commit by using commands like SET autocommit=0; in MySQL or by starting a transaction explicitly with BEGIN TRANSACTION; in many databases.

intermediate

Why might you want to disable auto-commit?

Disabling auto-commit lets you group multiple SQL statements into one transaction, so you can commit them all together or roll them back if something goes wrong, ensuring data consistency.

intermediate

What happens if an error occurs during a transaction when auto-commit is off?

If auto-commit is off and an error happens, you can roll back the entire transaction to undo all changes made since the transaction started, preventing partial updates.

What does auto-commit do in SQL?

A Deletes all data after each statement

B Prevents any changes from being saved

C Automatically saves each SQL statement as a transaction

D Requires manual commit after every statement

Auto-commit automatically saves each SQL statement as a transaction without needing a manual commit.

How do you disable auto-commit in MySQL?

A SET autocommit=0;

B COMMIT;

C ROLLBACK;

D START TRANSACTION;

The command SET autocommit=0; disables auto-commit in MySQL.

If auto-commit is off, what must you do to save changes?

A Run SELECT statement

B Use COMMIT command

C Use ROLLBACK command

D Nothing, changes save automatically

When auto-commit is off, you must use COMMIT to save changes permanently.

What is a benefit of turning off auto-commit?

A Group multiple statements into one transaction

B Automatically delete old data

C Speed up query execution

D Prevent any data changes

Turning off auto-commit lets you group multiple statements into a single transaction for better control.

What happens if an error occurs during a transaction with auto-commit off?

A All changes are saved anyway

B The error is ignored

C The database shuts down

D You can roll back all changes made in the transaction

With auto-commit off, you can roll back the entire transaction if an error occurs to avoid partial updates.

Explain what auto-commit behavior means in SQL and how it affects transactions.

Think about when changes become permanent in the database.

Describe why and how you would disable auto-commit in a database session.

Consider scenarios where you want to save or undo multiple changes together.