SQL - Transactions and Data Integrity
Identify the error in this SQL transaction block:
START TRANSACTION;
UPDATE accounts SET balance = balance - 100 WHERE id = 1;
COMMIT;
ROLLBACK;
Identify the error in this SQL transaction block: START TRANSACTION; UPDATE accounts SET balance = balance - 100 WHERE id = 1; COMMIT; ROLLBACK;
medium📝 Debug Q6 of 15
Step-by-Step Solution
Solution:
Step 1: Understand transaction flow
COMMIT finalizes changes; after commit, rollback has no effect.Step 2: Analyze the commands order
ROLLBACK after COMMIT is invalid because transaction is already closed.Final Answer:
ROLLBACK after COMMIT is invalid -> Option CQuick Check:
Rollback after commit error = B [OK]
Quick Trick: Rollback cannot follow commit in same transaction [OK]
Common Mistakes:
- Thinking rollback can undo committed changes
- Confusing savepoint usage
Master "Transactions and Data Integrity" in SQL
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