[Solved] You wrote this trigger function for DELETE:CREATE FUNCTION trg_delete_check() RETURNS trigger AS $ BEGIN IF NEW.... $ LANGUAGE plpgsql;What is the error in this function? | PostgreSQL

PostgreSQL - Triggers in PostgreSQL

You wrote this trigger function for DELETE:

CREATE FUNCTION trg_delete_check() RETURNS trigger AS $$
BEGIN
  IF NEW.id IS NULL THEN
    RAISE EXCEPTION 'ID cannot be null';
  END IF;
  RETURN OLD;
END;
$$ LANGUAGE plpgsql;

What is the error in this function?

ARAISE EXCEPTION syntax is wrong

BRETURN OLD is invalid in DELETE triggers

CUsing NEW in a DELETE trigger where only OLD is available

DFunction must return VOID, not trigger

Step-by-Step Solution

Solution:

Step 1: Check record variables in DELETE triggers
In DELETE triggers, the NEW record is not available because no new row is inserted or updated.
Step 2: Identify incorrect usage of NEW
The function incorrectly uses NEW.id, which causes an error. It should use OLD.id instead.
Final Answer:
Using NEW in a DELETE trigger where only OLD is available -> Option C
Quick Check:
DELETE triggers have OLD, not NEW = C [OK]

Quick Trick: Use OLD in DELETE triggers; NEW is unavailable [OK]

Common Mistakes:

Using NEW in DELETE triggers
Returning OLD incorrectly
Misunderstanding trigger return types

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You wrote this trigger function for DELETE:

Step 1: Check record variables in DELETE triggers

Step 2: Identify incorrect usage of NEW

Final Answer:

Quick Check:

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