谁能帮找找错啊。。为啥F5后不显示这个控件呢？

Question

后台代码
namespace OfficeChannel.UserCenter
{
    public partial class User_manage_moviedown : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {            DDLClassBind();
        }
        
        public void DDLClassBind()
        {
            using (OfficeChannel.OfficeChannelDataContext ocDC = new OfficeChannel.OfficeChannelDataContext(ConfigurationManager.ConnectionStrings["OfficeChannelConnectionString_Web"].ConnectionString))
            {
                var DL = from cd in ocDC.Class_Download
                         join cl in ocDC.Class on cd.classID equals cl.classID
                         select new { downloadTime = cd.DownloadTime, classtitle = cl.classTitle };
            }
        }
        protected void GridView1_PageIndexChanging(object sender, GridViewPageEventArgs e)
        {
            GridView1.PageIndex = e.NewPageIndex;
            DDLClassBind();
        }    }
}前台代码
<asp:GridView ID="GridView1" runat="server" BorderStyle="None" CellPadding="0" GridLines="None"
 AutoGenerateColumns="False" AllowPaging="True" ShowHeader="False" OnPageIndexChanging="GridView1_PageIndexChanging"
                            PageSize="6" UseAccessibleHeader="False">
                            <Columns>
                                <asp:TemplateField>
                                    <ItemTemplate>
                              <asp:Label ID="ProductType" runat="server" Text='<%# Eval("downloadTime") %>' ForeColor="orangered" />
                            <asp:Label ID="Label1" runat="server" Text='<%# Eval("DownloadTime") %>' ForeColor="orangered" />
                                    
                                    </ItemTemplate>
                                </asp:TemplateField>
                            </Columns>
                        </asp:GridView>

Answer 1

DDLClassBind();
===============>
if(!isPostback)
{
DDLClassBind();}

Answer 2

(!Page.IsPostBack) 加了也不行 看来还有别的错？

Answer 3

加个
if(!isPostback) 
{ 
 
}

Answer 4

 using (OfficeChannel.OfficeChannelDataContext ocDC = new OfficeChannel.OfficeChannelDataContext(ConfigurationManager.ConnectionStrings["OfficeChannelConnectionString_Web"].ConnectionString))
            {
                var DL = from cd in ocDC.Class_Download
                         join cl in ocDC.Class on cd.classID equals cl.classID
                         select new { downloadTime = cd.DownloadTime, classtitle = cl.classTitle };
                       
               GridView1.DataSource = DL;               GridView1.DataBind();
            }
我代码应该有这两句，1楼没发出来有这两句也不行 我怀疑这部分有问题。

Answer 5

是不是没有数据,所以不显示控件. datalist是这样.

Answer 6

using (OfficeChannel.OfficeChannelDataContext ocDC = new OfficeChannel.OfficeChannelDataContext(ConfigurationManager.ConnectionStrings["OfficeChannelConnectionString_Web"].ConnectionString))
            {
                var DL = from cd in ocDC.Class_Download
                         where cd.Username=="username"
                         select new { downloadTime = cd.DownloadTime};  
              上面查询1个表就没问题，用注释查询两个表就有问题！大哥们我哪写错了？
                         //join cl in ocDC.Class on cd.classID equals cl.classID
                         //select new { downloadTime = cd.DownloadTime, classtitle = cl.classTitle };
               GridView1.DataSource = DL;               GridView1.DataBind();

Answer 7

弱弱得问一下 
//join cl in ocDC.Class on cd.classID equals cl.classID    在这两个表得classID不是外键得时候 可以查询出结果嘛？
//select new { downloadTime = cd.DownloadTime, classtitle = cl.classTitle };

Answer 8

可以啊，主要是比较他们的classID是否相同
和键没关系的

Answer 9

var DL = from cd in ocDC.Class_Download
                         join cl in ocDC.Class on cd.classID equals cl.classID
                         select new { downloadTime = cd.DownloadTime, classtitle = cl.classTitle };               //在这里打印DL.Count()看看值是多少               GridView1.DataSource = DL;               GridView1.DataBind();

Answer 10

1、在PageLoad里面
if(!isPostback) 
{ 
   DDLClassBind(); 
} 2、给GridView控件邦定数据源！

Answer 11

 var DL = from cd in ocDC.Class_Download
                         where cd.Username=="username"
                         select new { downloadTime = cd.DownloadTime};  
              上面查询1个表就没问题，用注释查询两个表就有问题！大哥们我哪写错了？
                         //join cl in ocDC.Class on cd.classID equals cl.classID
                         //select new { downloadTime = cd.DownloadTime, classtitle = cl.classTitle };
               GridView1.DataSource = DL;               GridView1.DataBind();=======================
你在GridView1.DataSource = DL;之前Response.Write("<script language='javascript'>alert('"+DL.Count()+"')</script>");
看看你的DL有没有数据
如果没有就是查询有问题的