title: Selecting multiple checkbox inside gridview
body: <p>enter code hereI have a <code>CheckBox</code> inside a <code>GridView</code> template. When a <code>CheckBox</code> is checked, it should send a column value to a stored-procedure, and show the desired result in another <code>gridview</code>.
  When two checkboxes are checked, the values of two columns should be displayed in the other gridview. </p>
  
  <p>My problem is that clicking the second checkbox removes the value of first checkbox, and causes only the value of the second check box to be displayed in the other gridview.</p>
  
  <pre><code> protected void ChkRule_CheckedChanged(object sender, EventArgs e)
      {
          StringCollection sc = new StringCollection();
  
          for (int i = 0; i &lt; gdYojnaDtl.Rows.Count; i++)
          {
  
              string yojnaNo = "";
              CheckBox chl = (CheckBox)gdYojnaDtl.Rows[i].Cells[0].FindControl("CheckBox1");
              //CheckBox chl = (CheckBox)sender;
              if (chl != null)
              {
                  if (chl.Checked == true)
                  {
  
  
  
  
                      int rowsNo = (Convert.ToInt16(chl.ToolTip) - 1); 
                      yojnaNo = ((Label)gdYojnaDtl.Rows[rowsNo].FindControl("lblYojnaNo")).Text;
                      sc.Add(yojnaNo);
  
  
                  }
  
              }
          }
  
      foreach (string obj in sc)
      {
  
          objyojnadetail4.YojnaNo = obj;
          DataTable city = objyojnadetail4.Selectcity();
          gdCityDetail.DataSource = city;
  
  
  
          gdCityDetail.DataBind();
  
      }
  
  }
  
  
  
  
  
   &lt;Columns&gt;
                          &lt;asp:TemplateField HeaderText="Scheme Code"&gt;
                          &lt;ItemTemplate&gt;
                              &lt;asp:Label ID="lblYojnaNo" runat="server" Text='&lt;%#Eval("Yojna_No")%&gt;' /&gt;
  
                          &lt;/ItemTemplate&gt;
                          &lt;/asp:TemplateField&gt;
                          &lt;asp:TemplateField HeaderText="Scheme Name"&gt;
                           &lt;ItemTemplate&gt;
                       &lt;asp:Label ID="lblYojnaName" runat="server" Text='&lt;%#Eval("Yojna_Name")%&gt;' /&gt;
  
                          &lt;/ItemTemplate&gt;
                          &lt;/asp:TemplateField&gt;
                          &lt;asp:TemplateField HeaderText="Assistant Name"&gt;
                           &lt;ItemTemplate&gt;
                           &lt;asp:Label ID="lblAsstName" runat="server" Text=' &lt;%#Eval("Asst_Name")%&gt;' /&gt;
  
                          &lt;/ItemTemplate&gt;
                          &lt;/asp:TemplateField&gt;
                          &lt;asp:TemplateField HeaderText="Select for City"&gt;
                          &lt;ItemTemplate&gt;
                   &lt;asp:CheckBox ID="CheckBox1"  runat="server"    AutoPostBack="true" 
                    oncheckedchanged="ChkRule_CheckedChanged" 
                    ToolTip="&lt;%#Container.DataItemIndex+1 %&gt; "   CommandName="cbCity"/&gt;
  
  
  
  
  
                          &lt;/ItemTemplate&gt;
                          &lt;/asp:TemplateField&gt;
  
                      &lt;/Columns&gt;
  </code></pre>