If 语句确定表单上的框为空

Question

我有一个 Access 数据库，如果 DaysLeft 框小于 5 并且 MoveOutPacket 框为空，我希望从表单中触发一封电子邮件。

我有这个代码，但它没有通过电子邮件发送。

Private Sub DaysLeft_Change()

If (DaysLeft < 5) And (MoveOutPacket = Null) Then
    Dim Msg As String
    Msg = "Maintenance Team, we will recieve the keys for " & Property & " on " & Recieved_Keys & " please schedule cleaning and carpet cleaning if the unit is vacant."

    Dim O As Outlook.Application
    Dim M As Outlook.MailItem
    Set O = New Outlook.Application
    Set M = O.CreateItem(olMailItem)

    With M
        .BodyFormat = olFormatHTML
        .HTMLBody = Msg
        .To = "[email protected]"
        .Send
    End With

    Set M = Nothing
    Set O = Nothing

End If
End Sub

Answer 1

在 VBA 中，不能将任何内容与 Null 进行比较，甚至不能与 Null 进行比较。

使用 IsNull() 函数：

If DaysLeft < 5 And IsNull(MoveOutPacket) Then

可能还想纠正拼写：receive。