Question

我有一个页面，我试图根据下拉列表中的选择（cbLocation）填充gridview（gvClockings），以及从calendarextender（txtFrom和txtTo）输入文本框的from / to日期。

我已经测试了SQL语句，如果我在Access中运行它，它会得到预期的结果（并且我在此解决方案中使用类似的SQL与gridview在另一个表单上工作正常），但无论我选择什么，都在这个表单上在3个控件中，gridview不会显示任何记录。

cbLocation填充在Page_Load中，如下所示：

If Not Page.IsPostBack Then
        Dim ddl As DropDownList = cbLocation
        Dim ir As ListItem = New ListItem
        Dim ee As ListItem = New ListItem
        ir.Text = "IR Room"
        ir.Value = "IR Room"
        ee.Text = "Employee Exit"
        ee.Value = "Employee Exit"
        ddl.Items.Add(ir)
        ddl.Items.Add(ee)
    End If

然后我有以下代码来获取数据并填充gridview：

    Private Sub GetClockings(ByVal LLName As String, ByVal FromDate As String, ByVal ToDate As String)

    Dim conclock As OleDbConnection = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0; DATA SOURCE=\\xxx.xx.xxx.xx\AccuFace\pspcms.mdb;Jet OLEDB:Database Password=xxxxx;")
    Dim daClocking As OleDbDataAdapter = New OleDbDataAdapter
    Dim selectSQL As String = "SELECT efrLog.LFirstName, efrLog.LLastName, efrLog.LDepartment, efrLog.LDate, efrLog.LTime, efrLog.LType, efrLog.LLName FROM efrLog WHERE (((efrLog.LDate) Between [@FROMDATE] And [@TODATE]) AND ((efrLog.LLName)=[@LLName])) ORDER BY efrLog.LDepartment, efrLog.LTime"
    Dim selectCMD As OleDbCommand = New OleDbCommand(selectSQL, conclock)
    daClocking.SelectCommand = selectCMD

    selectCMD.Parameters.AddWithValue("@LLName", LLName)
    selectCMD.Parameters.AddWithValue("@FROMDATE", FromDate)
    selectCMD.Parameters.AddWithValue("@TODATE", ToDate)

    Dim dsClockings As DataSet = New DataSet
    daClocking.Fill(dsClockings, "efrLog")

    If dsClockings.Tables("efrLog").Rows.Count > 0 Then
        gvClockings.DataSource = dsClockings.Tables("efrLog")
        gvClockings.DataBind()
    Else
        lblNotFound.Text = "No clockings found for this location"
        lblNotFound.Visible = True
        Exit Sub
    End If
End Sub

上面的代码是从Button_click调用的，如下所示：

Dim LLName As String
    Dim FromDate As String = txtFrom.Text
    Dim ToDate As String = txtTo.Text


    If cbLocation.SelectedValue = "IR Room" Then
        LLName = "IR Room"
        GetClockings(LLName, FromDate, ToDate)
    End If

    If cbLocation.SelectedValue = "Employee Exit" Then
        LLName = "Employee Exit"
        GetClockings(LLName, FromDate, ToDate)
    End If

    lblLocation.Text = "Clocking report for " & cbLocation.SelectedValue.ToString() & " generated on " & Date.Now
    lblLocation.Visible = True

我已尽可能在本地调试（我在远程服务器上使用访问数据库，因此在本地运行时尝试填充数据集时会出现与连接字符串/权限相关的错误。我知道这是一个可怕的设置但这是我给予的工作，我不知道如何远程调试）并且据我所知，参数似乎正在接收正确的值（见下文）

Screen shot

我从数据库请求的数据肯定存在，所以我完全不知道为什么gridview没有填充。我们将非常感激地提供任何帮助。感谢

Answer 1

OleDb提供商不会按名称识别参数，而是根据他们的位置识别参数您按照命令字符串中显示的顺序添加参数值可能这会导致错误或不返回任何内容......

尝试以这种方式尊重命令文本中参数的定义顺序

Dim selectSQL As String = "SELECT .....FROM ... WHERE " & _
                          "(((efrLog.LDate) Between [@FROMDATE] And [@TODATE]) AND " & _
                          "((efrLog.LLName)=[@LLName])) " & _
                          "ORDER BY efrLog.LDepartment, efrLog.LTime"

selectCMD.Parameters.AddWithValue("@FROMDATE", FromDate)
selectCMD.Parameters.AddWithValue("@TODATE", ToDate)
selectCMD.Parameters.AddWithValue("@LLName", LLName)

Gridview没有使用参数查询 - VB从访问数据库填充

1 个答案: