'Order By' in Exists / Not Exists condition causing ORA-00907 in Apex4.1.1

Question

Hi Guys,
We have just upgraded from apex 3.2.1 to 4.1.1. on Oracle DB V11.2.0.1, while testing the apps in apex, I come across this problem.
When I have a page process that has a condition defined.
When Condition Type is Exists (SQL query returns at least one row) or Not Exists (SQL query returns no rows) and the Expression 1 is a query with an 'Order By' clause, e.g.
SELECT 123 FROM DUAL
ORDER BY 1
When the process is triggered, Apex 3.2.1 would evaluate the condition and run the process just fine, however Apex 4.1.1 would throw an error : ORA-00907: missing right parenthesis
I totally understand that an Order by clause in an Exists or Not Exists condition is unnecessary and agree that they shouldn't be there in the first place.
But unfortunately I am dealing with other developers codes and these conditions have been coded like these, probably from copy & paste codes.
Saying that, I also believe that an Apex upgrade should not stop anything that is working in previous releases without warning or provide a workaround, right?
I don't know if this affects other types of artifacts that can have a condition in apex when upgrading from 3.2.1, e.g Regions/Items/Computations/Validations etc.
Does anyone else get this behaviour? and is there an easy solution to fix these?
Ideally I don't want to go through all processes (and whatever other artifacts might be affected too) in all apps in all workspaces to check the condition type and remove the 'Order By' clause manually.
Thanks for any advises
Just did some more testing
'Computation' , 'Validations', 'Processes' and 'Branches' have the same problem, 3.2.1 takes 'Order By' fine in Exists/Not Exists condition, but 4.1.1 throws error.
'Regions', 'Buttons', 'Items' have consistent behaviour - both 3.2.1 and 4.1.1 throw error ORA-00907: missing right parenthesis, when page is rendered.
Edited by: Danny on 25/04/2012 20:07

Answer 1

Hi Danny,
that's interesting. I just had a look what happens when you use an EXISTS or NOT EXISTS condition type. The following final SQL statement will be generated with your above example. You can also see that if you run your application in debug mode.
select count(*) from sys.dual where exists (select 123 from dual order by 1)Executing that statement in SQL*Plus will also show the ORA-00907 error. It appears that the SQL parser doesn't allow an order by clause in an EXIST clause.
I wonder why this should have worked in previous versions, but I can only suspect that in the past we may just have executed
select 123 from dual order by 1which can be slightly slower because with the new EXISTS statement the SQL engine can stop processing earlier if it finds a record.
We try to be backward compatible as much as possible, but I doubt that we will change that back to the way it was before because of the performance penalty 99.9% of our customers would face.
Possible Workaround: You might be able to use the new "Application Search" to scan your application for "order by" and fix it for all hits where the attribute name is "Expression 1".
Regards
Patrick
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