Validation to check child records

[Carl Smith]

I have x2 tables Table A (Parent) and Table B (Children) with a relationship that uses a Constant field (=1)in Table A.

I want to be able to set up a validation on a Boolean field (1/0)"Valid" in Table A so that if changed - either to 1 or 0 - it checks for existing child records and displays a message to the user if records exist (e.g. Valid = 1 in Table B )

In the file supplied I've used the Count function but this doesn't seem to work. Any advice?

Validation.zip

[sbg2]

I find Filemakers validations confusing as do my users. In a case like yours I personally would probably go to a scripted validation. Example attached.

Validation2.zip

[Carl Smith]

Many thanks for your reply and file. Just what I needed!

Best Wishes