Datalist没有显示任何数据 [英] Datalist not showing any data

问题描述

我正在尝试在数据列表中显示数据，我的空白页面没有错误



这里是我的代码背后

i am trying to display data in data list , i am getting no error with blank page

here is my code behind

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        If Not Page.IsPostBack Then
            BindDataList()
        End If
       
    End Sub
    Protected Sub BindDataList()
        Dim ptype As String = Request.QueryString("Propert_Type")
        Dim wantsto As String = Request.QueryString("wantsto")
        Dim Category As String = Request.QueryString("Category")
        Dim SearchKeyword As String = Request.QueryString("SearchKeyword")
        Dim postedby As String
        If Request.QueryString("Postedby") = "All" Then
            postedby = "%%"
        Else : postedby = Request.QueryString("postedby")
        End If
        'Dim Postedby As String = Request.QueryString("Postedby")
        Dim MinBudget As String = Request.QueryString("MinBudget")
        Dim MaxBudget As String = Request.QueryString("MaxBudget")
        Dim Bedrooms As String = Request.QueryString("Bedrooms")
        Dim Bathrooms As String = Request.QueryString("Bathrooms")
        Dim State As String = Request.QueryString("State")
        Dim City As String = Request.QueryString("City")
        Dim Location As String = Request.QueryString("Location")

        Dim dt As New DataTable()
        con.Open()
        Try
            Dim s As String = "select date, Property_Id,Category,PropertyType,BedRooms,BathRooms,Area,Size,Price,Photo_path ,Posted_By,Subject,Description FROM Properties where Category=" & ptype & " and PropertyType=" & Category & " and PropertyFor =" & wantsto & " and Posted_By=" & postedby & "and bedrooms=" & Bedrooms & " and State=" & State & "and City=" & City & " and Location=" & Location & "and Keyword like '% & SearchKeyword & %' and Price between " & MinBudget & " and " & MaxBudget & " "
            Dim adp As New SqlDataAdapter(s, con)
            adp.Fill(dt)
            dlResidentional.DataSource = dt
            dlResidentional.DataBind()
            lblfr.Text = dlResidentional.Items.Count.ToString
        Catch ex As Exception
            Response.Write("Error occured: " & ex.Message.ToString())
        Finally
            dt.Clear()
            dt.Dispose()
            con.Close()
        End Try
    End Sub

来自评论的其他OP代码...

Other OP code from comment ...

<fieldset style="width: 500px;">
 <asp:datalist id="dlResidentional" runat="server" cellpadding="4" forecolor="#333333"
 repeatcolumns="1" backcolor="Olive" bordercolor="Olive" borderstyle="Groove"
 borderwidth="2px" height="170px" width="150px">


 <HeaderStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" />


 <table width="650" style="border: thin groove #87a310; border="2" >
 <tr>
 <td colspan="3" height="30" 
 style="font-family: 'Times New Roman', Times, serif; font-size: x-large; font-weight: bold; font-style: normal; color: #87a310"><img src="images/rupee.png" height="22" width="22" />  <%#DataBinder.Eval(Container.DataItem, "Price")%>  <%# DataBinder.Eval(Container.DataItem, "Subject")%></td>
 </tr>
 <tr>
 <td colspan="3" height="10" align="right">Property ID :<%#DataBinder.Eval(Container.DataItem, "Property_Id")%></td>
 </tr>
 <tr>
 <td rowspan="4" style="width: 154px">
 <asp:image runat="server" BorderColor="Olive" BorderStyle="Groove" BorderWidth="2px"
 Height="170px" Width="150px" ImageUrl='<%#DataBinder.Eval(Container.DataItem, "Photo_path") %>'
 GenerateEmptyAlternateText="True"> 
 </td>
 <td style="width: 217px" class="style2">     Size :<%# DataBinder.Eval(Container.DataItem, "Size")%></td>
 <td>   Covered Area :<%#DataBinder.Eval(Container.DataItem, "Area")%></td>
 </tr>
 <tr>
 <td style="width: 217px" class="style2">    Property Type :<%# DataBinder.Eval(Container.DataItem, "Category")%></td>
 <td>  Category : <%# DataBinder.Eval(Container.DataItem, "PropertyType")%></td>
 </tr>
 <tr>
 <td style="width: 217px" class="style2">   Type :<%# DataBinder.Eval(Container.DataItem, "BedRooms")%></td>
 <td>  Bathrooms : <%#DataBinder.Eval(Container.DataItem, "Bathrooms")%></td>
 </tr>
  
 <tr>
 <td class="style2" colspan="2">   Description :<%#DataBinder.Eval(Container.DataItem, "Description")%></td>
 </tr>
 <tr>
 <td colspan="3" height="10" align="right"></td>
 </tr>
 <tr>
 <td style="width: 154px">Posted By : <%#DataBinder.Eval(Container.DataItem, "Posted_By")%> </td>
 <td style="width: 217px" class="style2">View Details 
  
 </td>
 <td align="right">Posted on :<%#DataBinder.Eval(Container.DataItem, "Date")%></td>
 </tr>
 </table> 

 <SelectedItemStyle BackColor="#E2DED6" Font-Bold="True" ForeColor="#333333" />

 </fieldset>

推荐答案

在行上放置一个断点

Dim adp As New SqlDataAdapter(s, con)

并检查 s 中的SQL ...看到问题？你在varchar列上缺少单引号。



通过连接用户输入的字符串来创建sql绝对不是一个好主意。你让自己受到sql注入的支配。



使用参数化查询 - 参见 DataAdapter参数的参考 [ ^ ]



它不仅有助于防止数据库被被恶意用户摧毁，它也会为你处理所有那些讨厌的单引号。



发现潜在问题也容易得多

and examine the SQL in s ... see the problem? You are missing single quotation marks on the varchar columns.

Creating sql by concatenating strings that can be entered by a user is never a good idea. You leave yourself at the mercy of sql injection.

Use a parameterised query - see reference for DataAdapter Parameters[^]

Not only will it help prevent your database from being destroyed by a malicious user, it will also handle all those pesky single quotes for you.

It is also a lot easier to spot potential problems

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