Interactive Grid: Validation - Check for duplicated column entries over all rows

I had this situation now a few times and was always to lazy to write it down. :/

During my last task within the fabe project I hat to create a validation to check for duplicated entries inside an Interactive Grid.

Whenever I add “None of the above” twice, an error should occur:

This blog post from Lino Schilde was a good start for my final solution:

Interactive Grid Validation

Interactive Grid Validation

Validation of Type: PL/SQL Function (returning Error Text)

Code:

declare
  v_cnt number;
begin

– check only if insert or update (not delete “D”)
if :APEX$ROW_STATUS in (‘C’,‘U’) then

– select only if the current row is set to Y

– positive result if one answer was set to Y

select max(case when none_yn = ‘Y’ then 1 else 0 end)
  into v_cnt
  from answer
  where question_id = :P301_QUESTION_ID
  and answer_id != nvl(:ANSWER_ID,0)
  and :NONE_YN = ‘Y’;
 
  if v_cnt = 1 then
    return ‘Another answer was already set up with “None of the above”. You need to change and save it first.’;
  end if;

end if;
end;

My solution used a “max” aggregation within a “case when” trick to get the right result.

Maxime Tremblay gave me a really important tip:
If I add more then one row through the IG and press save. The validation is not gone be triggered.

To fix that you to add a unique index:
create unique index ANSWER_UK1 on ANSWER (
  case when NONE_YN = ‘Y’ then QUESTION_ID end
);

had to had a look at it :P

used this unique index:
create unique index ANSWERS_UK1 on ANSWERS (
case when NONE_YN = ‘Y’ then QUESTION_ID end
);

obviously, the error handling function would display a better/nicer error message to the user pic.twitter.com/u6bLWWpvjz

— askMax - Maxime Tremblay (@askMaxSolutions) April 2, 2020

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Tip of the day
All those meeting clients (Skype, Zoom, Hangouts …) can also be used for APEX friends and beer meetups. #beer #orclapex