[Solved] Consider this SQL transaction:BEGIN TRANSACTION; UPDATE accounts SET balance = balance - 100 WHERE id = 1;... COMMIT;What happens if the second UPDATE fails? | SQL

SQL - Transactions and Data Integrity

Consider this SQL transaction:

BEGIN TRANSACTION;
UPDATE accounts SET balance = balance - 100 WHERE id = 1;
UPDATE accounts SET balance = balance + 100 WHERE id = 2;
COMMIT;

What happens if the second UPDATE fails?

AOnly the second update fails, first update commits

BThe first update remains, second update is skipped

CBoth updates are rolled back, no balance changes occur

DThe transaction commits partially with errors

Step-by-Step Solution

Solution:

Step 1: Understand transaction atomicity
Transactions are atomic, meaning all operations succeed or none do.
Step 2: Analyze failure impact
If the second update fails, the entire transaction rolls back to keep data consistent.
Final Answer:
Both updates are rolled back, no balance changes occur -> Option C
Quick Check:
Transaction atomicity means rollback on failure = C [OK]

Quick Trick: If one step fails, transaction rolls back all changes [OK]

Common Mistakes:

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