AFTER UPDATE triggers in MySQL - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is an AFTER UPDATE trigger in MySQL?

An AFTER UPDATE trigger is a special procedure that runs automatically right after a row in a table is updated. It lets you perform extra actions based on the changes made.

beginner

When exactly does an AFTER UPDATE trigger execute?

It executes immediately after the update operation on a row finishes successfully, meaning the new data is already saved in the table.

intermediate

Can an AFTER UPDATE trigger modify the row that was just updated?

No, because the update is already done. To change the row during update, use a BEFORE UPDATE trigger instead.

beginner

Give a simple example use case for an AFTER UPDATE trigger.

You can use it to log changes to another table, like recording who updated a row and when, for audit purposes.

intermediate

How do you access the old and new values of a row inside an AFTER UPDATE trigger?

Use OLD.column_name for the value before update and NEW.column_name for the value after update.

When does an AFTER UPDATE trigger run in MySQL?

A Before the update operation starts

B Before the row is inserted

C After the update operation completes

D After a row is deleted

An AFTER UPDATE trigger runs immediately after a row has been updated successfully.

Which keyword lets you access the new value of a column inside an AFTER UPDATE trigger?

A OLD

B UPDATED

C CURRENT

D NEW

The NEW keyword refers to the new value of the column after the update.

Can an AFTER UPDATE trigger change the updated row's data?

A Yes, it can modify the row before saving

B No, the update is already done

C Yes, but only if the row is locked

D Only if the trigger is BEFORE UPDATE

AFTER UPDATE triggers run after the update is complete, so they cannot change the updated row.

What is a common use of AFTER UPDATE triggers?

A Log changes to another table

B Validate data before update

C Prevent updates

D Insert new rows

AFTER UPDATE triggers are often used to log changes or audit updates.

Which of these is NOT true about AFTER UPDATE triggers?

A They can stop the update from happening

B They can access OLD and NEW values

C They can perform additional actions

D They run after the update finishes

AFTER UPDATE triggers cannot stop or cancel the update because it already happened.

Explain what an AFTER UPDATE trigger is and when it runs.

Think about what happens right after you change data in a table.

Describe how you can use OLD and NEW keywords inside an AFTER UPDATE trigger.

Imagine comparing what changed in a row.