how to disallow identical dates and times?

[PJB]

I'm doing this on the fly so your probably gonna have to play with it a little, but try this:

Set rsappointment = dbappointment.Execute("select * from app_date_time") 
Do Until rsappointment.EOF 
   If rsappointment("app_date") = txtdate.Text And rsappointment("app_time") = txttime.Text Then 
   MsgBox "An appointment is already taken at that time. Please choose another.", , "choose another time" 
        Exit Do
    Else
    rsappointment.MoveNext
    End If
If rsappointment.EOF Then
  Goto continue
End IF
Loop