Question

我正在检查Access 2016表单中是否存在记录（如果存在），如果未将其添加到数据库，则显示一条消息。但是当txtRepGrpNumber为空时，我得到null的无效使用，如果不为空，即使数据库中已经存在它也会添加它。 RepGrpNumber是数据库中的一个数字字段。我的if陈述有误。

 Private Sub btnSave_Click()
Dim db As DAO.Database
Dim strSql As String
Dim message As String
Set db = CurrentDb
If Nz(CStr(Me.txtRepGrpNumber)) >= "" Then
strSql = "INSERT INTO dbo_TblSwShowRoom(RepGrpNumber, ViewOrder, RepCompany, AddressFull, Contact, Phone, Hours, ViewPhotos, ViewTour, ImageShow, Image, AddBy, DateAdded, DateChanged, ChangedBy, Enabled) " & _
         "VALUES('" & Me.txtRepGrpNumber & "','" & Me.txtViewOrder & "', '" & Me.txtRepCompany & "', '" & Me.txtAddressFull & "', '" & Me.txtContact & "', '" & Me.txtPhone & "', '" & Me.txtHours & "', '" & Me.txtViewPhotos & "', '" & Me.txtViewTour & "', '" & Me.txtImageShow & "', '" & Me.txtImage & "', '" & Me.txtAddBy & "', '" & Me.txtDateAdded & "', '" & Me.txtDateChanged & "', '" & txtChangedBy & "', '" & txtEnabled & "')"
    db.Execute strSql
    Me.SubFrmSwShowRoom.Requery
Else
    message = MsgBox("Cannot save because Group Number is Blank", vbCritical)
End If
'End If
Me.Requery
End Sub

Answer 1

CStr无法转换Null值。 CStr(Null)引发与您相同的错误。应该这样做：

If Nz(Me.txtRepGrpNumber, vbNullString) <> vbNullString Then

Answer 2

使用null无效的原因是，如果自打开表单以来txtRepGrpNumber的值未更改，并且该值为null，则CStr到达该字段时会抛出错误，错误使用null。

要修复它：

If Me.txtRepGrpNumber & vbNullString <> vbNullString Then

Access 2016运行时错误无效使用null

3 个答案: