UPDATE using a WITHIN GROUP

Question

I've written the below statement which returns the data in the format i need to update another table with however i'm struggling with the update

SELECT element_id,
  LISTAGG(cast(0 as varchar2(20))||', '|| VALUE, ' | ') WITHIN GROUP (ORDER BY display_order)
FROM EDRN.MD$$_ELEMENT_VALUES
WHERE element_id IN
  (SELECT element_id FROM EDRN_NEW.DATA_DICTIONARY)
GROUP BY element_id;

I done a basic convert into an UPDATE statement

    UPDATE EDRN_NEW.DATA_DICTIONARY
SET Choices = (LISTAGG(CAST(0 AS VARCHAR2(20))||', '|| VALUE, ' | ') WITHIN GROUP (ORDER BY display_order)
FROM EDRN.MD$$_ELEMENT_VALUES
WHERE element_id IN
  (SELECT element_id FROM EDRN_NEW.DATA_DICTIONARY)
GROUP BY element_id);

This received a "ORA-00934: group function is not allowed here" error. I'm unsure how to remove the group function but retain the data format i require?

Answer 1

You need a subquery to use listagg(). In this case, a correlated subquery:

update EDRN_NEW.DATA_DICTIONARY dd
    set choices = (SELECT LISTAGG(cast(0 as varchar2(20))||', '|| VALUE, ' | ') WITHIN GROUP (ORDER BY display_order)
                   FROM EDRN.MD$$_ELEMENT_VALUES ev
                   WHERE ev.element_id = dd.element_id
                  )
    where exists (select 1 
                  from EDRN.MD$$_ELEMENT_VALUES ev
                  where ev.element_id = dd.element_id 
                 );