Question

I’m new to MySQL procedures. I need to emulate some code that I usually do with PLpgSQL, something like this:

DROP FUNCTION IF EXISTS "aprtr_controlo_tabelas_ins_upd" () CASCADE;
CREATE OR REPLACE FUNCTION "aprtr_controlo_tabelas_ins_upd" ()         
RETURNS trigger AS

$BODY$
        BEGIN
            IF (TG_OP = 'INSERT') THEN
                NEW.data_ult_actual := current_timestamp;
                NEW.id_utiliz_ins := current_user;
            RETURN NEW;
            ELSEIF (TG_OP = 'UPDATE') THEN
                NEW.data_ult_actual := current_timestamp;
                NEW.id_utiliz_upd := current_user;
            RETURN NEW;
            END IF;

            RETURN NULL;
        END;
$BODY$
        LANGUAGE PLpgSQL
        CALLED ON NULL INPUT
        VOLATILE
        EXTERNAL SECURITY DEFINER; 

It is possible in MySQL to write procedures that return a trigger? Or better, can I use a procedure code and call it trigger in an operation of INSERT or UPDATE?

Best Regards,

Answer 1

MySQL only supports specific data types as function return types. As per MySQL documentation trigger is not a data type. Custom objects as data types is not a feature AFAIK. Supported data types are detailed here.

Referene: MySQL CREATE FUNCTION Syntax.