Which of the following correctly creates a row-level BEFORE INSERT trigger on a table named employees in PostgreSQL?

easy📝 Syntax Q3 of 15

PostgreSQL - Triggers in PostgreSQL

Which of the following correctly creates a row-level BEFORE INSERT trigger on a table named employees in PostgreSQL?

ACREATE TRIGGER emp_before_insert BEFORE INSERT ON employees FOR EACH ROW EXECUTE FUNCTION trg_func();

BCREATE TRIGGER emp_before_insert BEFORE INSERT ON employees FOR EACH STATEMENT EXECUTE FUNCTION trg_func();

CCREATE TRIGGER emp_before_insert AFTER INSERT ON employees FOR EACH ROW EXECUTE FUNCTION trg_func();

DCREATE TRIGGER emp_before_insert AFTER INSERT ON employees FOR EACH STATEMENT EXECUTE FUNCTION trg_func();

Step-by-Step Solution

Solution:

Step 1: Identify trigger timing and event
The question asks for a BEFORE INSERT trigger, so the timing is BEFORE and event is INSERT.
Step 2: Determine trigger level
Row-level triggers use FOR EACH ROW, statement-level use FOR EACH STATEMENT.
Step 3: Match syntax
CREATE TRIGGER emp_before_insert BEFORE INSERT ON employees FOR EACH ROW EXECUTE FUNCTION trg_func(); uses BEFORE INSERT, FOR EACH ROW, and executes the function correctly.
Final Answer:
Option A -> Option A
Quick Check:
Trigger timing and level keywords must match the requirement [OK]

Quick Trick: Row-level triggers use FOR EACH ROW, statement-level FOR EACH STATEMENT [OK]

Common Mistakes:

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