Limit Subform Selection

[ItsJeremy]

I'm in the process of getting away from Lookup fields and found a sample database that does what I'm looking to do.

Using the attached sample database from Allen Browne.

In the subform frmClientDisease found in the form frmClient, how do I limit the user's selection to be only one of each item, so the same disease isn't selected multiple times?

Thank you.

 

[isladogs]

I'm quite surprised if Allen Browne released this without explaining the point you raised.
One way would be to create a composite index on the fields ClientID and DiseaseID. This will prevent duplicates of any pairs of those values.