Hereby a possible solution. I assume you have some basic SQL and VBA knowledge.
First, set the row sources for the combo boxes with a SQL statement like:
Then, define an After Update event for the DOB combo box (that looks up/sets the Employee ID):
Finally, enter this VBA code into the AfterUpdate event:
Private Sub cmbDOB_AfterUpdate()
'Lookup the Employee ID
Me.txtEmployee.Value = DLookup("EmployeeID", "Employee", "Firstname='" & Me.cmbFirst & _
"' AND Surname='" & Me.cmbSur & _
"' AND DOB=#" & Format(Me.cmbDOB, "yyyy-mm-dd") & "#")
When you open the form in view mode, after selecting the combo boxes, the Employee ID is determined:
Hope this helps you in the right direction.