[Solved] You created this trigger function:CREATE FUNCTION check_phone_format() RETURNS trigger AS $ BEGIN IF NEW.phone !... What is the most probable cause? | PostgreSQL

PostgreSQL - Triggers in PostgreSQL

You created this trigger function:

CREATE FUNCTION check_phone_format() RETURNS trigger AS $$ BEGIN IF NEW.phone !~ '^\\+\\d{10,15}$' THEN RAISE EXCEPTION 'Invalid phone format'; END IF; RETURN NEW; END; $$ LANGUAGE plpgsql;

However, invalid phone numbers are still inserted. What is the most probable cause?

AThe trigger function does not return OLD instead of NEW.

BThe regular expression syntax is incorrect for PostgreSQL.

CThe trigger is not attached to the table or event properly.

DThe exception message is not descriptive enough.

Step-by-Step Solution

Solution:

Step 1: Understand the trigger function
The function checks phone format and raises an exception if invalid.
Step 2: Identify why invalid data passes
If invalid phones are inserted, likely the trigger is not firing.
Step 3: Common cause
Triggers must be explicitly created and attached to table events; missing this step means the function never runs.
Final Answer:
The trigger is not attached to the table or event properly. -> Option C
Quick Check:
Trigger must be created and linked to table [OK]

Quick Trick: Trigger function alone doesn't enforce rules without trigger creation [OK]

Common Mistakes:

Assuming function runs without creating trigger
Misunderstanding regex syntax in PostgreSQL
Returning OLD instead of NEW in BEFORE INSERT triggers

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You created this trigger function:

Step 1: Understand the trigger function

Step 2: Identify why invalid data passes

Step 3: Common cause

Final Answer:

Quick Check:

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