Postgresql Create Trigger Before Deleting A Row

Question

so i have these two tables:

 -- Table user
 columns: id,name,surname, password,token,earnedmoney


 -- Table addlisting
 columns: id, user_fk,price,date_added

Here is my problem: I would like to create a trigger so that when I delete a listing from the table addlisting, the price of the listing gets added to the column "earnedmoney" which is in the table user.

Could somebody help me? Thank you!

Answer 1

CREATE OR REPLACE FUNCTION add_money() RETURNS trigger AS
$$BEGIN
   UPDATE "user" SET earnedmoney = earnedmoney + OLD.price
      WHERE id = OLD.user_fk;
   RETURN OLD;
END;$$ LANGUAGE plpgsql;

CREATE TRIGGER add_money
   BEFORE DELETE ON addlisting FOR EACH ROW
   EXECUTE PROCEDURE add_money();

It could also be an AFTER trigger, that would make no difference.