Yes/No Field Validation

[pdbe]

I want to add a field validation which says that only one record in the database is allowed to have the value 'YES' in the field (or no record has the value 'YES') and all the others must be 'NO'. Can this be done using a calculation to validate the field?

Thanks in anticipation.

[Søren Dyhr]

No define the field as number, and format is as boolean. Then attach a script when you define the field as an invisible button as well.

This script contains just one line:

Set Field [ myYesNo; Mod(myYesNo + 1;2) ]

This script toggles the value between the two layout options you have entered in the formatting of the number.

Whether or not you should need a default value in the field is down to your requirements, but if it's so, make an autoenter value either 0 or 1...

--sd