Validation won't work - exists

Question

I have a simple form that fires off a procedure to create a clone of the previously shown record, except they must provide a new revision number. I need to check to see if the newly entered revision already exists, and if so, tell them.
I've tried an item level as well as a page level validation, exists, and non-exists. It just doesn't seem to work. I either get an error on anything I enter (exists), or anything will pass thru (not exists).
I have a sql statement that if any rows are returned, I want an error message. This is entered into expression 1...
select * from EQUIP_HEAD
WHERE
EQUIP_HEAD.GEMS_HULL = :P101_HULL_ID AND
EQUIP_HEAD.EQUIPMENT = :P315_EQUIPMENT AND
EQUIP_HEAD.REVISIONNUM = :P315_REVISION
What am I doing wrong? I would think that a 'not exist' would be the correct type, and that the validation would 'pass' if there were no rows. I know there are rows where the revision number is '3', but certainly not when the revision number is 'xxxx'.
I am truly baffled.
Clayton

Answer 1

Holy Batman!
The only thing I changed, was the error message block of the validation. It said in line field validation, and I had no associated item selected. For whatever the reason, I selected the correct field. And bingo, it works.
I created the validation using the wizard, and selected the field I wanted to validate The error message had been popping up on the correct field, as well as the top of the form. And now suddenly, it works after I manually go in and select the field I want to validate.
I swear, I like APEX. I really do. But weird stuff happens. This one cost me half a day.
Clayton