Access While循环中Broken SelectedItems比较

Question

为了允许Access数据库的可移植性，如果要复制文件夹到另一台计算机，我想强迫用户选择其文件夹。但是，在尝试测试文件夹的路径时遇到了绊脚石。

在下面的代码中，未注释掉if语句块，但上面的while语句无效。我得到：

运行时错误'5'：无效的过程调用或参数。

我看过Tools > References，并且适当的部件似乎已经准备就绪。我已经尝试过fd.SelectedItems.Count = 0，但这并不能防止传递不需要的字符串。

Private Sub btn_CorrectPath_Click()
   Dim sHostName As String, strSQL As String, sFolder As String
   Dim rs As Recordset, db As Database, fd As FileDialog
   Dim intResult As Integer

   Set db = CurrentDb
   ' Get Host Name / Get Computer Name
   sHostName = Environ$("computername")
   Set rs = CurrentDb.OpenRecordset("SELECT * FROM t_ComputerInfo")

   If rs!ComputerName <> sHostName Then
      Set fd = Application.FileDialog(msoFileDialogFolderPicker)
      fd.AllowMultiSelect = False
      fd.Title = "Select database folder"

      intResult = fd.Show
      While intResult = False
         intResult = fd.Show
         While fd.SelectedItems(1) = vbNullString 'folder path was not selected
            intResult = fd.Show
         Wend
      Wend
      sFolder = fd.SelectedItems(1)
      strSQL = "UPDATE t_ComputerInfo SET [t_ComputerInfo].[ComputerName] = '" & sHostName & _ 
             & " [t_ComputerInfo].[DBPath] = '" & sFolder & "' WHERE [t_ComputerInfo].[ID] = 1"
      CurrentDb.Execute strSQL, dbFailOnError

'      If fd.Show = True Then 'Action button was pressed
'         MsgBox ("Directory was given. fd.SelectedItems(1)= " & fd.SelectedItems(1))
'         If fd.SelectedItems(1) <> vbNullString Then
'            sFolder = fd.SelectedItems(1)
'            strSQL = "UPDATE t_ComputerInfo SET [t_ComputerInfo].[ComputerName] = '" & sHostName & _
                     "', [t_ComputerInfo].[DBPath] = '" & sFolder & "' WHERE [t_ComputerInfo].[ID] = 1"
'            MsgBox ("SQL statement = " & vbCrLf & strSQL)
'            CurrentDb.Execute strSQL, dbFailOnError
'         End If
'      Else 'Cancel button was pressed
'         sFolder = fd.SelectedItems(1)
'         MsgBox ("The location of the database is required and will be requested later. fd.SelectedItems(1)= " & sFolder)
'      End If
      Set fd = Nothing
   End If

   db.Close
End Sub

Answer 1

我看不到需要嵌套While。考虑：

Dim booResult As Boolean
...
While booResult = False
    If fd.Show = True Then 'folder path was selected
        booResult = True
        sFolder = fd.SelectedItems(1)
    End If
Wend

Answer 2

首先，请注意，您在此串联中将与号加倍了：

strSQL = "UPDATE t_ComputerInfo SET [t_ComputerInfo].[ComputerName] = '" & sHostName & _
         & " [t_ComputerInfo].[DBPath] = '" & sFolder & "' WHERE [t_ComputerInfo].[ID] = 1"
         ^----- Here 

---

对于您的其余代码，我相信您可以完全删除while循环（除非您真的希望用户在选择文件夹之前一直陷入循环……？）。>

我可能会提出以下建议：

Private Sub btn_CorrectPath_Click()
    Dim fld As String
    Dim pcn As String

    pcn = Environ$("computername")
    If Nz(DLookup("computername", "t_computerinfo"), "") <> pcn Then
        With Application.FileDialog(4)
            .AllowMultiSelect = False
            .Title = "Select Database Folder"
            If .Show Then fld = .selecteditems(1)
        End With
        If fld <> "" Then
            With CurrentDb.CreateQueryDef("", "update t_computerinfo t set t.computername = @pc, t.dbpath = @pth where t.id = 1")
                .Parameters(0) = pcn
                .Parameters(1) = fld
                .Execute dbFailOnError
            End With
        End If
    End If
End Sub
[这里，我用DLookup代替打开记录集，因为在查询单个值时这似乎是过分的，但是，您可能希望为DLookup提供一些条件。

我还使用了连接值的参数化SQL语句，因为这是更好的做法，并且还可以处理数据类型。