SQL - Triggers
Identify the correct syntax to create an AFTER UPDATE trigger named
log_changes on the sales table for audit logging:Identify the correct syntax to create an AFTER UPDATE trigger named log_changes on the sales table for audit logging:
easy📝 Syntax Q3 of 15
Step-by-Step Solution
Solution:
Step 1: Trigger timing and event
The trigger must be AFTER UPDATE on the sales table.Step 2: Row-level trigger
FOR EACH ROW is required to capture each updated row.Step 3: Correct syntax
CREATE TRIGGER log_changes AFTER UPDATE ON sales FOR EACH ROW BEGIN INSERT INTO audit (sale_id, old_amount, new_amount) VALUES (OLD.id, OLD.amount, NEW.amount); END; correctly uses OLD and NEW references and proper syntax.Final Answer:
Option A -> Option AQuick Check:
AFTER UPDATE + FOR EACH ROW + correct OLD/NEW usage [OK]
Quick Trick: Use AFTER UPDATE and FOR EACH ROW with OLD and NEW [OK]
Common Mistakes:
- Using BEFORE UPDATE instead of AFTER UPDATE
- Omitting FOR EACH ROW
- Using FOR EACH STATEMENT when row-level is needed
- Incorrect event type like INSERT instead of UPDATE
Master "Triggers" in SQL
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