Select a value from dropdown list with the ID and display the ID selected in gridview
<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>
