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

easy📝 Syntax Q3 of 15

PostgreSQL - Triggers in PostgreSQL

ACREATE PROCEDURE audit_log_func() AS $$ BEGIN INSERT INTO audit_table VALUES (OLD.*); END; $$ LANGUAGE sql;

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

CCREATE FUNCTION audit_log_func() RETURNS void AS $$ BEGIN INSERT INTO audit_table VALUES (NEW.*); END; $$ LANGUAGE plpgsql;

DCREATE FUNCTION audit_log_func() RETURNS trigger AS $$ BEGIN UPDATE audit_table SET data = NEW.data; RETURN OLD; END; $$ LANGUAGE plpgsql;

Step-by-Step Solution

Solution:

Step 1: Identify correct function signature
Trigger functions must return type 'trigger'.
Step 2: Check function body
It should insert audit info and return NEW or OLD appropriately.
Step 3: Validate language
plpgsql is the correct procedural language for triggers.
Final Answer:
CREATE FUNCTION audit_log_func() RETURNS trigger AS $$ BEGIN INSERT INTO audit_table VALUES (NEW.*); RETURN NEW; END; $$ LANGUAGE plpgsql; -> Option B
Quick Check:
Trigger functions return 'trigger' and use plpgsql [OK]

Quick Trick: Trigger functions must return 'trigger' type [OK]

Common Mistakes:

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