title: Select a value from dropdown list with the ID and display the ID selected in gridview
body: <p>My problem is that I can only select the first index, but I want to select all values in  the dropdown list. I tried multiple combinations of selectedvalue or selectedindexchanged, but it still not working.</p>
  
  <pre><code>&lt;%@ Page Language="C#" Debug="true"%&gt;
  &lt;%@ import Namespace="System.Data" %&gt;
  &lt;%@ import Namespace="System.Data.SqlClient" %&gt;
  &lt;!DOCTYPE html&gt;
  
  &lt;html xmlns="http://www.w3.org/1999/xhtml"&gt;
  &lt;head runat="server"&gt;
      &lt;link rel="text/css" href="style1.css"/&gt;
    &lt;script language="c#" runat="server"&gt;
        string str = "Data Source=.;uid=sa;pwd=123;database=InventoryRouting";
            protected void Page_Load(object sender, EventArgs e)
            {
                SqlConnection con = new SqlConnection(str);
                string com = "Select * from Plant";
                SqlDataAdapter adpt = new SqlDataAdapter(com, con);
                DataTable dt = new DataTable();
                adpt.Fill(dt);
                drop.DataSource = dt;
                drop.DataBind();
                drop.DataTextField = "PlantID";
                drop.DataValueField = "PlantID";
                drop.DataBind();
            }
            protected void Button1_Click1(object sender, EventArgs e)
            {
                SqlConnection con = new SqlConnection(str);
                SqlCommand cmd = new SqlCommand("select * from Plant where PlantID = '"+     drop.SelectedValue +"'", con);
                SqlDataAdapter Adpt = new SqlDataAdapter(cmd);
                DataTable dt = new DataTable();
                Adpt.Fill(dt);
                grid.DataSource = dt;
                grid.DataBind();
            }
        &lt;/script&gt;
  &lt;/head&gt;
  &lt;body&gt;
      &lt;center&gt;
          &lt;h1 style="background-color:red; width:500px;height:50px;"&gt;Plant     Information&lt;/h1&gt;&lt;hr&gt;
      &lt;form id="form1" runat="server"&gt;
      &lt;div id="right"&gt;
          Choose Plant ID to View Information&lt;asp:DropDownList ID="drop" runat="server"     Width="100px" AutoPostBack="true" OnSelectedIndexChanged="Button1_Click1"&gt;    &lt;/asp:DropDownList&gt;
          &lt;br /&gt;
          &lt;br /&gt;
          &lt;!--&lt;asp:Button ID="Button1" runat="server" Text="View"     OnClick="Button1_Click1" Style="height: 26px" /&gt;--&gt;
          &lt;br /&gt;
          &lt;br /&gt;
          &lt;asp:GridView ID="grid" runat="server" BackColor="White" BorderColor="#999999"
              BorderStyle="None" BorderWidth="1px" CellPadding="3" GridLines="Vertical"&gt;
              &lt;AlternatingRowStyle BackColor="#DCDCDC" /&gt;
              &lt;FooterStyle BackColor="#CCCCCC" ForeColor="Black" /&gt;
              &lt;HeaderStyle BackColor="#000084" Font-Bold="True" ForeColor="White" /&gt;
              &lt;PagerStyle BackColor="#999999" ForeColor="Black" HorizontalAlign="Center"     /&gt;
              &lt;RowStyle BackColor="#EEEEEE" ForeColor="Black" /&gt;
              &lt;SelectedRowStyle BackColor="#008A8C" Font-Bold="True" ForeColor="White" /&gt;
              &lt;SortedAscendingCellStyle BackColor="#F1F1F1" /&gt;
              &lt;SortedAscendingHeaderStyle BackColor="#0000A9" /&gt;
              &lt;SortedDescendingCellStyle BackColor="#CAC9C9" /&gt;
              &lt;SortedDescendingHeaderStyle BackColor="#000065" /&gt;
          &lt;/asp:GridView&gt;
      &lt;/div&gt;
      &lt;/form&gt;
          &lt;/center&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>How can I select all ID from my dropdown list? Please help me</p>