Question

I have the following trigger:

CREATE OR REPLACE FUNCTION record_deleted_item() RETURNS TRIGGER AS $$
BEGIN
    IF (select number_itens from grup where NEW.gruop_id = group_id) != 0 THEN
    UPDATE gruop SET number_itens= (number_itens-1) WHERE gruop_id=NEW.gruop_id;
   END IF;
RETURN NEW;
END; $$
LANGUAGE plpgsql;

CREATE TRIGGER deleted_item
BEFORE DELETE ON item
FOR EACH ROW EXECUTE PROCEDURE record_deleted_item();

In my if-else clause I should check if the column value number_items from group table is not 0. How could I check it? The way I’ve done returns me an error.

Answer 1

SELECT it into variable and compare to zero. You may also want to check if SELECT actually returned anything.

DECLARE
    ni bigint;
BEGIN
    SELECT number_itens INTO ni FROM ...;
    IF NOT FOUND THEN
    END IF;
    IF NI != 0 THEN
    END IF;
END