Re: Function to set up variable inside it

CREATE FUNCTION change_trigger() RETURNS trigger AS $$
       BEGIN
               IF      TG_OP = 'INSERT'
               THEN
                       INSERT INTO logging.t_history (tabname, schemaname, operation, new_val)
                               VALUES (TG_RELNAME, TG_TABLE_SCHEMA, TG_OP, row_to_json(NEW));
                       RETURN NEW;
               ELSIF   TG_OP = 'UPDATE'
               THEN
                       INSERT INTO logging.t_history (tabname, schemaname, operation, new_val, old_val)
                               VALUES (TG_RELNAME, TG_TABLE_SCHEMA, TG_OP,
                                       row_to_json(NEW), row_to_json(OLD));
                       RETURN NEW;
               ELSIF   TG_OP = 'DELETE'
               THEN
                       INSERT INTO logging.t_history (tabname, schemaname, operation, old_val)
                               VALUES (TG_RELNAME, TG_TABLE_SCHEMA, TG_OP, row_to_json(OLD));
                       RETURN OLD;
               END IF;
       END;

$$ LANGUAGE 'plpgsql' SECURITY DEFINER;