gridview没有显示什么是解决方案 [英] gridview not displayed what's the solution

问题描述

我的代码如下......

 <   asp：标签    ID   =   lbl_selcat    runat  < span class =code-keyword> =  server   文本  = 选择目录： >  
 <   asp：DropDownList     ID   =  ddl_catalogue    runat   = 服务器 >  
 
 <   asp：GridView     ID   =  GridView1 < span class =code-attribute>   runat   =  server      DataKeyNames   =  id   < span class =code-attribute> onrowcancelingedit   =  GridView1_RowCancelingEdit    
   
                       onrowdeleting   =  GridView1_RowDeleting     onrowediting   = < span class =code-keyword> GridView1_RowEditing    
   
                       onrowupdating   =  GridView1_RowUpdating  
   
                 AutoGenerateColumns   =  False    BorderColor   = 黑色    BorderWidth   =  2px    
   
                      < span class =code-attribute> HeaderStyle-BackColor   = ＃FF6600 < span class =code-attribute>   HeaderStyle-BorderStyle   =  NotSet    
   
                       HeaderStyle-Font-Bold   =  True    HeaderStyle-Font-斜体  = 真    
   
                < span class =code-attribute>       HeaderStyle-Font-Size   = 中    HeaderStyle-Font-Underline   = 真    
   
        < span class =code-attribute>               HeaderStyle-ForeColor   = 白色 >  
 <  列 >  
 
 <   asp：BoundField     DataField  < span class =code-keyword> =  id    HeaderText   =  ID    /  >  
 <   asp：BoundField     DataField   = < span class =code-keyword> cat_id    HeaderText   =  cat_id    /  >  
 <   asp：BoundField     HeaderText   = 名称    DataField   =  name    /  >  
 <   asp：BoundField     DataField   =  type    HeaderText   = 输入    /  >  
 <   asp：BoundField    < span class =code-attribute> DataField   =  price    HeaderText   = 价格    /  >  
 <   asp：ImageField     DataImageUrlField   =  image    HeaderText   = 图片 >  
 <   control   style  < span class =code-attribute>   height   =  200px    width   =   200px    /  >  
 
 < span class =code-keyword><   asp：BoundField     DataField   =  description    HeaderText   = 描述     /  >  
 <   asp：CommandField     ShowEditButton   =  True    /  >  
 <   asp：CommandField     ShowDeleteButton   =  True    /  >  
 <   /列 >  
 
 <   HeaderStyle     BackColor   =  ＃FF6600    Font-Bold   =  Tru e    Font-Italic   = 真   字体大小  = 中   字体下划线  =  True    ForeColor   = 白色 >  <   / HeaderStyle  >  

aspx.cs文件

  protected  空隙 Page_Load（ object  sender，EventArgs e）
 {
  if （IsPostBack！ =  true ）
 {
 ddl_catalogue.DataSource = GetData（）; 
 ddl_catalogue.DataValueField =   cat_id; 
 ddl_catalogue.DataTextField =   cat_nm; 
 ddl_catalogue.DataBind（）; 
 ddl_catalogue.Items.Insert（ 0 ， new  ListItem（  ---选择---，  0\" ））; 
 
 
} 
 
} 
 
 受保护  void  ddl_catalogue_SelectedIndexChanged（ object  sender，EventArgs e）
 {
 SqlConnection con =  new  SqlConnection（ @  Data Source = .\SQLEXPRESS; AttachDbFilename = | DataDirectory | \Database.mdf; Integrated Security = True; User Instance = True）; 
 SqlCommand cmd =  new  SqlCommand（  select *来自cat_detail，其中cat_id =' + ddl_catalogue.SelectedValue +  '，con） ; 
 con.Open（）; 
 SqlDataReader dr = cmd.ExecuteReader（）; 
  if （dr.HasRows）
 {
 GridView1.DataSource = dr; 
 GridView1.DataBind（）; 
 
} 
 dr.Close（）; 
 con.Close（）; 
} 
 DataTable GetData（）
 {
 DataTable dt =  new  DataTable（）; 
 SqlConnection con =  new  SqlConnection（ @ 数据源= .\SQLEXPRESS; AttachDbFilename = | DataDirectory | \Database.mdf; Integrated Security = True; User Instance = True）; 
 SqlCommand cmd =  new  SqlCommand（  select *来自目录，con）; 
 con.Open（）; 
 SqlDataAdapter sda =  new  SqlDataAdapter（cmd）; 
 sda.Fill（dt）; 
  return  dt; 
} 
 

解决方案

绑定时使用 DataAdapter GridView 。

 SqlDataAdapter dataAdapter =  new  SqlDataAdapter （cmd，con）; 
 DataTable dt =  new  DataTable（）; 
 dataAdapter.Fill（dt）; 
 
 GridView1.DataSource = dt; 
 GridView1.DataBind（）; 

在初始化 SqlCommand 对象时也使用参数化查询。

my code as below...

<asp:Label ID="lbl_selcat" runat="server" Text="Select catalogue:">
       <asp:DropDownList ID="ddl_catalogue" runat="server">
       
      <asp:GridView ID="GridView1" runat="server"  DataKeyNames="id" onrowcancelingedit="GridView1_RowCancelingEdit" 

          onrowdeleting="GridView1_RowDeleting" onrowediting="GridView1_RowEditing" 

          onrowupdating="GridView1_RowUpdating"

       AutoGenerateColumns="False" BorderColor="Black" BorderWidth="2px" 

          HeaderStyle-BackColor="#FF6600" HeaderStyle-BorderStyle="NotSet" 

          HeaderStyle-Font-Bold="True" HeaderStyle-Font-Italic="True" 

          HeaderStyle-Font-Size="Medium" HeaderStyle-Font-Underline="True" 

          HeaderStyle-ForeColor="White">
           <columns>
           
             <asp:BoundField DataField="id" HeaderText="ID" />
               <asp:BoundField DataField="cat_id" HeaderText="cat_id" />
               <asp:BoundField HeaderText="Name" DataField="name" />
               <asp:BoundField DataField="type" HeaderText="Type" />
               <asp:BoundField DataField="price" HeaderText="Price" />
               <asp:ImageField DataImageUrlField="image" HeaderText="IMAGE">
               <controlstyle height="200px" width="200px" />
               
               <asp:BoundField DataField="description" HeaderText="Description" />
               <asp:CommandField ShowEditButton="True" />
               <asp:CommandField ShowDeleteButton="True" />
              </columns>

<HeaderStyle BackColor="#FF6600" Font-Bold="True" Font-Italic="True" Font-Size="Medium" Font-Underline="True" ForeColor="White"></HeaderStyle>

aspx.cs file

protected void Page_Load(object sender, EventArgs e)
   {
       if (IsPostBack != true)
       {
           ddl_catalogue.DataSource = GetData();
           ddl_catalogue.DataValueField="cat_id";
           ddl_catalogue.DataTextField = "cat_nm";
           ddl_catalogue.DataBind();
           ddl_catalogue.Items.Insert(0, new ListItem("---Select---", "0"));


       }

   }

 protected void ddl_catalogue_SelectedIndexChanged(object sender, EventArgs e)
   {
       SqlConnection con = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Database.mdf;Integrated Security=True;User Instance=True");
       SqlCommand cmd = new SqlCommand("select * from cat_detail where cat_id='"+ddl_catalogue.SelectedValue+"'", con);
       con.Open();
       SqlDataReader dr = cmd.ExecuteReader();
       if (dr.HasRows)
       {
         GridView1.DataSource = dr;
         GridView1.DataBind();

       }
               dr.Close();
               con.Close();
   }
   DataTable GetData()
   {
           DataTable dt=new DataTable();
           SqlConnection con = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Database.mdf;Integrated Security=True;User Instance=True");
           SqlCommand cmd=new SqlCommand("select * from catalogue",con);
           con.Open();
           SqlDataAdapter sda=new SqlDataAdapter(cmd);
           sda.Fill(dt);
           return dt;
   }

解决方案

Use DataAdapter while binding GridView.

SqlDataAdapter dataAdapter = new SqlDataAdapter(cmd, con);
DataTable dt = new DataTable();
dataAdapter.Fill(dt);

GridView1.DataSource = dt;
GridView1.DataBind();

Also use Parameterized query while initializing a SqlCommand object.

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