unique records in a join table
I'm working on a solution that has 3 tables: Volunteers, Oportunities and a join table. There can be only one Volunteer-Oportunity record in the join table.
I have a portal on the Volunteer form that allows me to select Opportunities for the Volunteer record I'm currently working on and add a record to the join table. This works fine.
What I'm trying to do is display a custom dialog box that gives the user a clearer message that a duplicate entry is being made, only gives them the option to cancel the entry and removes the duplicate entry from the join table.
I've created a calculation field in the join table that has both foriign keys and checked the Unique box. When I enter a duplicate Volunteer-Opportunity record I get the standard Filemaker dialog box that alerts me to the fact that I'm entering a duplicate entry.
Thanks for any help.