由于某种原因，当我应用我的dgvBarcodes.Datasource.Defaultview.Rowfilter=strDGVBarcodesFilter时，它正在查找(列"测试"(，而不是筛选列"上的行；LongDescription=测试"；。这是出乎意料的行为。如何使用.DefaultView.RowFilter根据"；LongDescription=测试"；？
本例中的strDGVBarcodesFilter＝"；LongDescription=测试"；，当鼠标移到上面时，我得到的错误是"；System.Data.EvaluateException："找不到列[test]。">
事件处理程序：
If txtLongDescription2.Text IsNot Nothing Then Dim strLongDescription As String = txtLongDescription2.Text Dim strLongDescriptionFilter As String = "" If strLongDescription = "" Then strLongDescriptionFilter = "" Else strLongDescriptionFilter = "LongDescription=" & strLongDescription End If Dim strDGVBarcodesFilter As String = fnBuildFilterString(strMainBrandFilter, strSubBrandFilter, strLongDescriptionFilter) dgvBarcodes.DataSource.DefaultView.Rowfilter = strDGVBarcodesFilter End If
筛选字符串生成器函数；
Private Function fnBuildFilterString(strFilterComponent1 As String, strFilterComponent2 As String, Optional strFilterComponent3 As String = "", Optional strFilterComponent4 As String = "", Optional strFilterComponent5 As String = "") As String
'Essentially it builds this; strMainFilter = strFilterComponent1 & " AND " & strFilterComponent2 & " AND " & strFilterComponent3 & " AND " & strFilterComponent4 & " AND " & strFilterComponent5
Dim strMainFilter As String = "" 'Reset the masterfilter string to be empty
If strFilterComponent1 <> "" Then 'If the filter component isn't empty
If strMainFilter = "" Then 'And if the masterfilter is empty
strMainFilter = strFilterComponent1 'Adds the filter component to the masterfilter string
Else 'The masterfilter isn't empty
strMainFilter &= " AND " & strFilterComponent1 'then it adds " AND " &field to the masterfilter string
End If
Else 'Filter component is empty, do nothing
End If 'check next component
If strFilterComponent2 <> "" Then 'If the filter component isn't empty
If strMainFilter <> "" Then 'And if the masterfilter isn't empty
strMainFilter &= " AND " & strFilterComponent2 'then it adds " AND " &field to the masterfilter string
Else 'The masterfilter is empty
strMainFilter = strFilterComponent2 'Adds the filter component to the masterfilter string
End If
Else 'Filter component is empty, do nothing
End If 'check next component
If strFilterComponent3 <> "" Then 'If the filter component isn't empty
If strMainFilter <> "" Then 'And if the masterfilter isn't empty
strMainFilter &= " AND " & strFilterComponent3 'then it adds " AND " &field to the masterfilter string
Else 'The masterfilter is empty
strMainFilter = strFilterComponent3 'Adds the filter component to the masterfilter string
End If
Else 'Filter component is empty, do nothing
End If 'check next component
If strFilterComponent4 <> "" Then 'If the filter component isn't empty
If strMainFilter <> "" Then 'And if the masterfilter isn't empty
strMainFilter &= " AND " & strFilterComponent4 'then it adds " AND " &field to the masterfilter string
Else 'The masterfilter is empty
strMainFilter = strFilterComponent4 'Adds the filter component to the masterfilter string
End If
Else 'Filter component is empty, do nothing
End If 'check next component
If strFilterComponent5 <> "" Then 'If the filter component isn't empty
If strMainFilter <> "" Then 'And if the masterfilter isn't empty
strMainFilter &= " AND " & strFilterComponent5 'then it adds " AND " &field to the masterfilter string
Else 'The masterfilter is empty
strMainFilter = strFilterComponent5 'Adds the filter component to the masterfilter string
End If
Else 'Filter component is empty, do nothing
End If 'check next component
Return strMainFilter
End Function
想想你在那里做什么。如果你在VB代码中这样做：
Dim someStringVariable As String
'...
If someStringVariable = Test Then
你会期望将该变量与文本"进行比较吗；测试"？当然不是，因为那里没有文字。您必须将文本用双引号括起来，以表明它是一个文本String。如果您希望在SQL代码中使用文本(过滤器是SQLWHERE子句(，则需要执行等效操作。如何在SQL代码中表示文本？单引号。
以下是做你想做的事情的正确方法：
strLongDescriptionFilter = $"LongDescription = '{strLongDescription}'"
和：
Dim criteria As New List(Of String)
If Not String.IsNullOrWhitespace(strFilterComponent1) Then
criteria.Add(strFilterComponent1)
End If
'Etc.
Return String.Join(" AND ", criteria)
你还可以做其他的改进，但这可能已经足够迈出第一步了。