access-training-courses - Form problem

Paul,

I assume you want the error message to come up and actually stop them from using that option. If it was me I would go about this in a slightly different way. I would create another table with the options in, with a column for the option, a column for the ID and a column for a Boolean value of true or false. Then using VBA I would populate the drop list using the options where in the Boolean column the value is false. Then when you select an option it will set the value in the Boolean column to true and will no longer appear in the drop down list.

By using this method you will not present your users with an option they cannot use, and there will be no need for an error message.

However if you want to stick to your original idea I would use VBA and a query to find out if any other record has used the option you just select if they have then show error message and if it is not used then allow.

Hope this helps
David