I assume your combo is based on a table listing the events to choose from (lets say tblEventList) and you have another scheduling table listing the customer ids, event id (from the first table) and event date, lets name it tblEventSchedule. You need to modify the row source of the combo by joining in the scheduling table and adding to the criteria row to only show the EventID and EventName Where dCount("*","tblEventSchedule","EventDate=#" & Forms!frmYourForm!EventDate & "#")>0; save this as a query named qrySelectedEventForSelectedDate or something similar. And finally in the Enter or GotFocus event of the combo have:
Code:
if dCount("*","qrySelectedEventForSelectedDate")>0
Me.cboEventList.RowSource="qrySelectedEventForSelectedDate" 'first event already selected
Else
Me.cboEventList.RowSource="tblEventList" 'no selection yet
End If
Cheers,