Which of the following is the correct syntax to create a trigger function for audit logging in PostgreSQL?

easy📝 Syntax Q12 of 15

PostgreSQL - Triggers in PostgreSQL

ACREATE TRIGGER audit_log BEFORE INSERT ON audit_table EXECUTE FUNCTION log_changes();

BCREATE FUNCTION audit_log() RETURNS void AS $$ BEGIN UPDATE audit_table SET changed = TRUE; END; $$ LANGUAGE sql;

CCREATE FUNCTION audit_log() RETURNS trigger AS $$ BEGIN INSERT INTO audit_table VALUES (OLD.*); RETURN NEW; END; $$ LANGUAGE plpgsql;

DCREATE FUNCTION audit_log() RETURNS trigger AS $$ BEGIN INSERT INTO audit_table VALUES (NEW.*); RETURN OLD; END; $$ LANGUAGE plpgsql;

Step-by-Step Solution

Solution:

Step 1: Check function return type and language
Trigger functions must return type 'trigger' and use 'plpgsql' language.
Step 2: Verify correct use of OLD and NEW
For audit logging on updates/deletes, OLD.* is used to capture previous data; function returns NEW to continue operation.
Final Answer:
CREATE FUNCTION audit_log() RETURNS trigger AS $$ BEGIN INSERT INTO audit_table VALUES (OLD.*); RETURN NEW; END; $$ LANGUAGE plpgsql; -> Option C
Quick Check:
Trigger function syntax = CREATE FUNCTION audit_log() RETURNS trigger AS $$ BEGIN INSERT INTO audit_table VALUES (OLD.*); RETURN NEW; END; $$ LANGUAGE plpgsql; [OK]

Quick Trick: Trigger functions return 'trigger' and use plpgsql [OK]

Common Mistakes:

Master "Triggers in PostgreSQL" in PostgreSQL

9 interactive learning modes - each teaches the same concept differently

Want More Practice?

15+ quiz questions · All difficulty levels · Free