ORACL PL/SQL Trigger Using Two different tables

Question

I am not experienced in PL/SQL topics a lot, besides writing migration SQLs and some basic triggers. Because of that i will ask my question directly to have at least one start point into my trigger for table that i am expecting.

We have below tables :

VIB: Varchar
Locale: Varchar
Status : Varchar
Released : boolean

I need a trigger on D2C_EVENT_GENERATION_MASTER table, the requirement is that, some system will give inserts to this table for "vib" column without LOCALE values for vibs . So our expectation is to calculate locales(find appropriate locales from release_table) before insert operation of that system, by asking RELEASE_TABLE for appropriate locales that is existing for that VIB , and released flag is 'true'.

CREATE OR REPLACE TRIGGER BL_D2C_EVENT_GENERATION_MASTER
   BEFORE INSERT
   ON D2C_EVENT_GENERATION_MASTER
   FOR EACH ROW
DECLARE
   l_locale  varchar2(100);
BEGIN
    if :NEW.locale is null then
    for rec in (select locale from RELEASE_TABLE@pdpe.mch.bshg.com where vib=:NEW.vib AND released = 1)
    loop
    INSERT INTO d2c_event_generation_master (vib,locale) VALUES (:NEW.vib,rec.locale);
    end loop;
    DELETE FROM d2c_event_generation_master where vib=:NEW.vib AND locale is null;
    end if;
END;

I am about to create this trigger, but only one exception occurs that i couldn't fix. When i insert a row with null locale value in table like this :

  INSERT INTO D2C_EVENT_GENERATION_AP (vib) values ('GP200046');

It gets locales from other table but inserts three rows :

GP200046    fr-BE
GP200046    nl-BE
GP200046    null

I don't want to see 'null' here, i tried some execute immediate or some other staff, but couldn't find something.

Can you please help there ?

Answer 1

here is a trigger before insert to get value from the release table:

CREATE OR REPLACE TRIGGER BI_D2C_EVENT_GENERATION_MASTER
   BEFORE INSERT
   ON D2C_EVENT_GENERATION_MASTER
   FOR EACH ROW
DECLARE
   l_locale   varchar2(100);
BEGIN
    if :NEW.locale is null then
        select locale INTO l_locale from release where vib=:NEW.vib;
        :NEW.locale := l_locale;
    end if;
END;
/

EDIT:

For the second solution I suggest creating a procedure:

CREATE OR REPLACE PROCEDURE MI_D2C_EVENT_GENERATION_MASTER (p_vib number, p_locale varchar2)
IS
 l_vib number := p_vib;
 l_locale varchar2(100) := p_locale;
BEGIN   
    MERGE INTO D2C_EVENT_GENERATION_MASTER event
    USING (SELECT vib, locale from D2C_EVENT_GENERATION_MASTER) old_event
    ON (event.vib = l_vib
        and event.locale = l_locale)
    WHEN MATCHED THEN
        UPDATE SET event.STATUS = 'NEW'
        WHERE event.STATUS != 'NEW'
    WHEN NOT MATCHED THEN 
        INSERT (vib,locale,status) VALUES (l_vib, l_locale, 'STATUS')';
END;
/