[Solved] You run this SQL code:BEGIN TRANSACTION;UPDATE accounts SET balance = balance - 100 WHERE id = 5;COMMIT;ROLLBACK;What is the effect of the final ROLLBACK? | SQL

SQL - Transactions and Data Integrity

You run this SQL code:

BEGIN TRANSACTION;
UPDATE accounts SET balance = balance - 100 WHERE id = 5;
COMMIT;
ROLLBACK;

What is the effect of the final ROLLBACK?

AIt undoes the UPDATE and restores the original balance.

BIt causes a syntax error because ROLLBACK cannot follow COMMIT.

CIt has no effect because changes were already committed.

DIt commits the changes again.

Step-by-Step Solution

Solution:

Step 1: Understand COMMIT effect
COMMIT saves all changes permanently, so the UPDATE is finalized.
Step 2: Analyze ROLLBACK after COMMIT
ROLLBACK after COMMIT does nothing because there is no active transaction to undo.
Final Answer:
It has no effect because changes were already committed. -> Option C
Quick Check:
ROLLBACK after COMMIT = no effect [OK]

Quick Trick: ROLLBACK only undoes uncommitted changes [OK]

Common Mistakes:

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