Ms access If-then-Else语句访问2010_Ms Access_If Statement_Vba

Ms access If-then-Else语句访问2010

ms-access if-statement vba

Ms access If-then-Else语句访问2010,ms-access,if-statement,vba,Ms Access,If Statement,Vba,我一直在论坛上寻找答案，但似乎找不到答案。对不起，代码太长了基本上，我想做的是，如果第一个“if”语句没有返回任何内容，则在“Billing_preadpayment”字段中设置值“$0.00”。目前，如果我运行代码，但没有匹配项，“Billing_Prepayment”字段将变为空白。不知道我错过了什么。我试过了；“”中，空，为空。什么都没起作用 Private Sub AccountID_Change() ' Adds prepaid values to invoice

我一直在论坛上寻找答案，但似乎找不到答案。对不起，代码太长了

基本上，我想做的是，如果第一个“if”语句没有返回任何内容，则在“Billing_preadpayment”字段中设置值“$0.00”。目前，如果我运行代码，但没有匹配项，“Billing_Prepayment”字段将变为空白。不知道我错过了什么。我试过了；“”中，空，为空。什么都没起作用

   Private Sub AccountID_Change()
    ' Adds prepaid values to invoice
      If DLookup("Total_Prepayment", "quePrepayment", "[AccountID] = Forms![frmInvoices]!AccountID And [Billing_Month] = Forms![frmInvoices]!Billing_Month And [Billing_Year] = Forms![frmInvoices]!Billing_Year") = Null Then
        Billing_Prepayment = "$0.00"
      Else
        Billing_Prepayment = DLookup("Total_Prepayment", "quePrepayment", "[AccountID] = Forms![frmInvoices]!AccountID And [Billing_Month] = Forms![frmInvoices]!Billing_Month And [Billing_Year] = Forms![frmInvoices]!Billing_Year")
End If      
End Sub

  If (DLookup("Total_Prepayment", "quePrepayment", "[AccountID] = Forms![frmInvoices]!AccountID And [Billing_Month] = Forms![frmInvoices]!Billing_Month And [Billing_Year] = Forms![frmInvoices]!Billing_Year") & "") = ""