DataSource错误：UllReferenceExeption未被用户代码处理

Question

我最初将GridView表的数据库问题发送到数据库，但我已经纠正了它。

我遇到的主要问题是，无论我使用<td> Classified Ads </td>链接还是按钮，当我点击它时，Visual Studio中的代码仍会启动，而不管它是否都在代码If Not IsPostBack Then。

我认为我的问题是，无论何时点击链接，页面都会加载。我知道这是事实，因为当我调试它并单击链接时，Visual Studio代码仍然运行。

如何解决此问题？

其中链接是（文字说明：分类广告）：

<table align="center" border="0" cellpadding="0" cellspacing="0" width="100%">
                <tr>
                    <td align="left" valign="middle" width="87%">


                        &nbsp;&nbsp;<a href="Index.aspx" style="text-decoration:none;" ><font color="000000" 
                        face="Verdana, Arial, Helvetica, sans-serif" size="2.7"><b>Classified Ads</b></font>
                               </a>

                        &nbsp;<font color="000000" face="Verdana, Arial, Helvetica, sans-serif" size="2.7" style="padding-top:5px">></font>&nbsp;

                        <a style="text-decoration:none;" href="WF_DisplayAll.aspx">
                        <font color="000000" face="Verdana, Arial, Helvetica, sans-serif" size="2.7"><b>All Classified Ads</b></font>
                        </a>

                     </td>

                     <td width="13%" valign="middle" align="right">
                            <a style="text-decoration:none;" href="Login.aspx">
                            <font color="000000" face="Verdana, Arial, Helvetica, sans-serif" size="2.7"> Admin&nbsp;&nbsp;&nbsp;&nbsp</font></a>
                     </td>
                </tr>
             </table>

Visual Studio：

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load


    'OleDbDataAdapterSecurity.SelectCommand.CommandText = "SELECT Addate, username, Phonenbr, email, description FROM t_classifieds"


    'Dim OracleDataAdapterAds As OracleDataAdapter = New OracleDataAdapter
    'OracleDataAdapterAds.SelectCommand = strSelectAds

    ' Makes so it runs the first time
    If Not IsPostBack Then
        Dim conn As OleDbConnection = New OleDbConnection("Provider=""******"";user id=" & strUserID & ";data source=" & strDatabase & ";password=" & strPssWd)

        'Display All Classified Ads listed in the Database based on the following format/order
        'Date    Name    Home Phone Number     Description

        Dim ClassifiedStr As OleDbCommand = New OleDbCommand("SELECT classid, Addate, username, Phonenbr, email, description FROM t_classifieds", conn)
        Dim OracleDataAdapterAds As OleDbDataAdapter = New OleDbDataAdapter
        OracleDataAdapterAds.SelectCommand = ClassifiedStr
        Dim DsAds As DataSet = New DataSet
        DsAds.Clear()
        OracleDataAdapterAds.Fill(DsAds, "t_classifieds")
        DisplayAllClassifieds.DataSource = DsAds
        DisplayAllClassifieds.DataMember = "t_classifieds"
        DisplayAllClassifieds.DataBind()
    End If
End Sub

Answer 1

我想我是如何修复它的（不知道这个进程会被调用的是什么）但是我需要修复我的Response.Redirect按钮链接版本。

换句话说，按钮的属性我对PostBackUrl进行了编辑：

对于VB代码，我添加了“True”部分：

Protected Sub Main_Click(sender As Object, e As EventArgs) Handles Main.Click

    Response.Redirect("Index.aspx", True)
End Sub