Dim sql_test1 As String
 
sql_test1 = "SELECT DISTINCT Grafik_A From Tabelle_A Union SELECT DISTINCT" & _
  "Grafik_B From Tabelle_B Union SELECT DISTINCT Grafik_C From Tabelle_C"
 
 If OpenRecordset(mRs, mConn, sql_test1, adOpenStatic, adUseClient, _
   adLockOptimistic) Then
 
   Do Until mRs.EOF
   Combo1.AddItem mRs.Fields("Grafik_A" & ", " & "Grafik_B" & ", " & "Grafik_C")
   mRs.MoveNext
   Loop
 
 End If

Combo1.AddItem mRs.Fields("Grafik_A" & ", " & "Grafik_B" & ", " & "Grafik_C")