问题描述
我正在我的列表视图 (ssql)
上应用搜索过滤器。当结果没有找到记录时,我想取消该操作,否则 Listview 为空,我无法撤消过滤器。
Private Sub LoadStandardListview(Optional ByVal sFilter As String = "")
Try
Dim ssql As String
Dim sSubStr As String
Dim strs As String
If sFilter = "" Then
ssql = "SELECT Id,[Document Type],[Document Name],disnummer,XPostnummer,[Last Accessed],[Document Location] FROM Archief WHERE ([Document Type] Is Not Null) AND ([disnummer] Is Not Null) AND ([XPostnummer] Is Not Null) AND ([Last Accessed] Is Not Null) ORDER BY Id DESC"
Else
sSubStr = " AND [Document Name] LIKE '%" + sFilter + "%' "
ssql = "SELECT Id,[Document Location] FROM Archief WHERE ([Document Type] Is Not Null) AND ([disnummer] Is Not Null) AND ([XPostnummer] Is Not Null) AND ([Last Accessed] Is Not Null)" + sSubStr + "ORDER BY Id DESC"
End If
strs = "SELECT Count(*) FROM Archief"
Dim cmd As New OleDb.OleDbCommand(ssql,con)
Dim cmd2 As New OleDb.OleDbCommand(strs,con)
Dim dr As OleDb.OleDbDataReader = cmd.ExecuteReader
Dim dis As String
Dim docImage As VariantType
Dim items As New List(Of ListViewItem)
dr.Read()
Dim recordCount As Long
recordCount = cmd2.ExecuteScalar
ListView1.BeginUpdate()
ListView1.Items.Clear()
While dr.Read
If dr("Document Type").ToString = "PDF" Or dr("Document Type").ToString = "pdf" Then
docImage = (ImageList1.Images.Count - 1)
ElseIf dr("Document Type").ToString = "DOC" Or dr("Document Type").ToString = "doc" Then
docImage = (ImageList1.Images.Count - 3)
ElseIf dr("Document Type").ToString = "PPT" Or dr("Document Type").ToString = "ppt" Then
docImage = (ImageList1.Images.Count - 2)
End If
dis = dr("Last Accessed").Substring(0,dr("Last Accessed").IndexOf(" "))
items.Add(New ListViewItem(New String() {"",dr("Document Name").ToString,dr("disnummer"),dr("XPostnummer"),dis,dr("Id").ToString,dr("Document Location").ToString},docImage))
End While
ListView1.Items.AddRange(items.ToArray)
ListView1.EndUpdate()
sNumRec = items.Count
If sFilter <> "" Then
ToolStripTextBox3.Text = sNumRec + " Documents"
Else
ToolStripTextBox3.Text = recordCount.ToString + " Documents"
End If
Catch ex As Exception
MsgBox(ex.Message)
End Try
End Sub
有没有办法在没有找到记录时取消操作并用所有记录再次填充列表视图?
解决方法
您在哪里使用了 cmd2.ExecuteScalar
的值,即 recordCount
?试试这个
If recordCount > 0 Then
While dr.Read
...
End While
dr.Close()
Else
`Refill listview with no filter`
End If
,
Dim sSQL As String
Dim sSubStr As String
If sFilter = "" Then
sSQL = "SELECT Id,[Document Type],[Document Name],DISnummer,XPostnummer,[Last Accessed],[Document Location] FROM Archief ORDER BY Id DESC"
Else
sSubStr = "WHERE [Document Name] LIKE '%" + sFilter + "%' "
sSQL = "SELECT Id,[Document Location] FROM Archief " + sSubStr + " ORDER BY Id DESC"
End If
Dim cmd As New OleDbCommand(sSQL,con)
Using dr As OleDbDataReader = cmd.ExecuteReader
Dim dis As String
Dim docImage As VariantType
Dim items As New List(Of ListViewItem)
If dr.HasRows() Then
ListView1.BeginUpdate()
ListView1.Items.Clear()
While dr.Read
If dr("Document Type").ToString = "PDF" Or dr("Document Type").ToString = "pdf" Then
docImage = (ImageList1.Images.Count - 1)
ElseIf dr("Document Type").ToString = "doc" Or dr("Document Type").ToString = "docx" Then
docImage = (ImageList1.Images.Count - 3)
ElseIf dr("Document Type").ToString = "ppt" Or dr("Document Type").ToString = "pptx" Then
docImage = (ImageList1.Images.Count - 2)
ElseIf dr("Document Type").ToString = "xls" Or dr("Document Type").ToString = "xlsx" Then
docImage = (ImageList1.Images.Count - 4)
End If
dis = dr("Last Accessed").Substring(0,dr("Last Accessed").IndexOf(" "))
items.Add(New ListViewItem(New String() {"",dr("Document Name").ToString,dr("DISnummer").ToString,dr("XPostnummer").ToString,dis,dr("Id").ToString,dr("Document Location").ToString},docImage))
End While
ListView1.Items.AddRange(items.ToArray)
ListView1.EndUpdate()
Else
MsgBox("Nothing was found.",Title)
End If
dr.Close()
End Using
我稍微改变了我的代码。我把
Using dr as New OleDbDataReader = cmd.ExecuteReader
If dr.HasRows() Then