Dim JanE, FebE, MrzE, AprE, MaiE, JunE, JulE, AugE, SepE, OktE, NovE, DezE As _
  String
Dim JanA, FebA, MrzA, AprA, MaiA, JunA, JulA, AugA, SepA, OktA, NovA, DezA As _
String
Dim JanED, FebED, MrzED, AprED, MaiED, JunED, JulED, AugED, SepED, OktED, _
NovED, DezED As Double
Dim JanAD, FebAD, MrzAD, AprAD, MaiAD, JunAD, JulAD, AugAD, SepAD, OktAD, _
NovAD, DezAD As Double
Dim Jan, Feb, Mrz, Apr, Mai, Jun, Jul, Aug, Sep, Okt, Nov, Dez As Double
 
Set Rs = New ADODB.Recordset
Set Rs2 = New ADODB.Recordset
 
Rs.Open "Select SUM(Einnahme) As Summe From Kassenbuch Where Monat = 'Feb'", _
  Cn, adOpenDynamic, adLockOptimistic
Rs2.Open "Select * From Kassenbestände Where Monat = 'Feb'", Cn, adOpenDynamic, _
adLockOptimistic
    If Rs.Fields("Summe").Value = "" Then
        FebE = "0"
    Else
        FebE = Rs.Fields("Summe")
    End If
Rs.Close
Rs2.Close
 
Rs.Open "Select SUM(Ausgabe) As Summe From Kassenbuch Where Monat = 'Feb'", Cn, _
  adOpenDynamic, adLockOptimistic
Rs2.Open "Select * From Kassenbestände Where Monat = 'Feb'", Cn, adOpenDynamic, _
adLockOptimistic
    If Rs.Fields("Summe").Value = "" Then
        FebA = "0"
    Else
        FebA = Rs.Fields("Summe")
    End If
 
Rs.Close
Rs2.Close
 
FebED = CDbl(FebE)
FebAD = CDbl(FebA)
Feb = FebED - FebAD
 
Rs2.Open "SELECT * FROM KAssenbestände Where Monat = 'Feb'", Cn, adOpenDynamic, _
  adLockOptimistic
Rs2.Fields("Bestand").Value = Feb
 
Rs2.Update
Rs2.Close

FebAD = CDbl(FebA)