基于查询的特定列表框的空白列不被识别为空或空 [英] The blank column of the particular List Box based on query is not recognized as either empty or null

问题描述

列表框： SearchList 从以下查询中获取数据： Machine_Search 。因此，输入我的序列号进入搜索文本框，然后按按钮搜索，然后选择显示在 SearchList上的记录。选择记录后，然后按编辑。条件是，如果我使用序列号搜索的记录在 End_Date 中具有空字段，则记录会顺利进​​行。但是，如果使用序列号搜索的记录在 End_Date 中具有日期，它将提示一个msgbox，然后关闭然后再次打开表单。问题在于无法检测到 End_Date 为空还是空，并且无论条件如何都会提示msgbox。

The Listbox: SearchList get data from the query: Machine_Search.So how it works is i input my Serial Number into the Search textbox and press the button search then select the record displayed on the SearchList. When the record is selected, i then press edit. The condition is that if the record that i search using Serial Number have empty field in the End_Date it will go on smoothly. However if the record that is search using Serial Number have a date in the End_Date it will prompt a msgbox and, close and open the form again. The issue lies at where it cannot detect if End_Date is null or empty and will prompt the msgbox regardless of the condition.

表格：机器

查询：Machine_Search-它查询表格：具有以下形式的机器： Machine_Load 会填充表格中一半的字段，而另一个将由 Machine_Unload /

Query: Machine_Search - It query the table:Machine where there is a form called: Machine_Load which fills half the field in the table and the other will be filled by Machine_Unload/

Form：Machine_Unload

Form:Machine_Unload

是否可以解决此问题？

Private Sub cmdSearch_Click()
Dim check As String
    DoCmd.OpenQuery "Machine_Search"
    DoCmd.Close acQuery, "Machine_Search"
    SearchList.Requery

    If SearchList.ListCount = 0 Then
        MsgBox ("No records found.")
        DoCmd.Close
        DoCmd.OpenForm "Machine_Unload"
        Exit Sub
    End If

    Me.cmdEdit.Enabled = True
    Me.cmdSearch.Enabled = False
    Me.txtSN.Enabled = True
    Me.txtDate.Enabled = True
    Me.txtTime.Enabled = True
    Me.CheckTime.Enabled = True
    Me.ListSuccess.Enabled = True
    Me.txtOperator.Enabled = True
    Me.txtRemarks.Enabled = True
    Me.txtSearch.Enabled = False
    Me.txtSN.SetFocus
End Sub

Private Sub cmdEdit_Click()

On Error GoTo Err_cmdEdit_Click
Dim SN_Value As String
Dim Date_Value As String
    If Me.SearchList.ListIndex > -1 Then
        SN_Value = Me.SearchList.Value
        Date_Value = Me.SearchList.Column(5)

        If Not IsEmpty(Date_Value) Then
            MsgBox ("The Unload data for this Serial Number have been filled, Please confirm with cell leader.")
            DoCmd.Close
            DoCmd.OpenForm "Esagon_Unload"
            Exit Sub
        End If
    End If

    'check whether there exists data in list
    If Not (Me.SearchList.Recordset.EOF And Me.SearchList.Recordset.BOF) Then
        'get data to text box control
        With Me.SearchList.Recordset
            Me.txtSN = .Fields("Serial_Number")
            'store id of serial number in tag of txtSN in case id is modified
            Me.txtSN.Tag = .Fields("Serial_Number")
            'Disable button edit
            Me.cmdEdit.Enabled = False
            Me.cmdUpdate.Enabled = True

        End With
    End If

End_Err:
Exit Sub


Err_cmdEdit_Click:
MsgBox ("Select the Serial Number." & vbCrLf & "Please try again and click on the Serial Number below.")
DoCmd.Close
DoCmd.OpenForm "Machine_Unload"
Resume End_Err

End Sub

SELECT Machine.Serial_Number, Machine.End_Date, Machine.End_Time, Machine.End_System_Time, Machine.End_Operator, Machine.Success, Machine.End_Remarks
FROM Machine
WHERE (((Machine.Serial_Number)=[Forms]![Machine_Unload]![txtSearch]));

推荐答案

IsEmpty 不适用这种用法。尝试：

IsEmpty is not for this usage. Try:

If Not IsNull(Date_Value) Then

或：

If Nz(Date_Value) <> "" Then

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