[Solved] Given this AFTER UPDATE trigger:CREATE TRIGGER trg_after_update AFTER UPDATE ON products FOR EACH ROW EXECUTE FUNCTION log_update();What will happen if an UPDATE statement modifies multiple rows? | PostgreSQL

PostgreSQL - Triggers in PostgreSQL

Given this AFTER UPDATE trigger:

CREATE TRIGGER trg_after_update AFTER UPDATE ON products FOR EACH ROW EXECUTE FUNCTION log_update();

What will happen if an UPDATE statement modifies multiple rows?

AThe log_update() function runs only once after all rows update.

BThe trigger runs before the update statement.

CThe trigger will not run for multiple rows.

DThe log_update() function runs once for each updated row.

Step-by-Step Solution

Solution:

Step 1: Analyze FOR EACH ROW behavior
FOR EACH ROW triggers execute once per affected row, even if multiple rows are updated.
Step 2: Confirm timing and frequency
Since it's an AFTER UPDATE trigger, the function runs after each row update, multiple times if multiple rows change.
Final Answer:
The log_update() function runs once for each updated row. -> Option D
Quick Check:
FOR EACH ROW triggers run per row updated [OK]

Quick Trick: FOR EACH ROW triggers run once per affected row [OK]

Common Mistakes:

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Given this AFTER UPDATE trigger: