[Solved] Given this trigger snippet for audit logging:CREATE TRIGGER audit_update AFTER UPDATE ON products FOR EACH... END;What will be inserted into audit_log when a product's price changes from 100 to 120? | SQL

SQL - Triggers

Given this trigger snippet for audit logging:

CREATE TRIGGER audit_update AFTER UPDATE ON products FOR EACH ROW BEGIN INSERT INTO audit_log (product_id, old_price, new_price) VALUES (OLD.id, OLD.price, NEW.price); END;

What will be inserted into audit_log when a product's price changes from 100 to 120?

A(product_id: NULL, old_price: 100, new_price: 120)

B(product_id: product's id, old_price: NULL, new_price: NULL)

C(product_id: product's id, old_price: 120, new_price: 100)

D(product_id: product's id, old_price: 100, new_price: 120)

Step-by-Step Solution

Solution:

Step 1: Understand OLD and NEW in triggers
OLD refers to the row before update, NEW refers to the row after update.
Step 2: Analyze the insert statement
The trigger inserts OLD.id, OLD.price, and NEW.price, so product_id is the old id, old_price is 100, new_price is 120.
Final Answer:
(product_id: product's id, old_price: 100, new_price: 120) -> Option D
Quick Check:
OLD = before update, NEW = after update [OK]

Quick Trick: OLD = old row, NEW = new row in update triggers [OK]

Common Mistakes:

Mixing OLD and NEW values
Assuming NULL values for unchanged columns
Confusing product_id with price values

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Given this trigger snippet for audit logging:

Step 1: Understand OLD and NEW in triggers

Step 2: Analyze the insert statement

Final Answer:

Quick Check:

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