Question

I want to assign same datasource to multiple DropDownLists in a form, when the page loads, only the first drop down list has filled the content of datasource, others are empty, what’s the missing point? thanks for answers. Here are the codes;

<form id="form1" runat="server">    
    <asp:ScriptManager ID="scriptManager1" runat="server"></asp:ScriptManager>
<asp:UpdatePanel ID="panel1" runat="server" UpdateMode="Conditional">
    <ContentTemplate>
     <div id="div1" align="center">
      <table>
       <tr>
         <td><b>Brand-Model</b></td>
         <td><asp:TextBox ID="brandText" runat="server" BorderStyle="Inset"></asp:TextBox></td>
         <td><asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ControlToValidate="brandText" Display="Dynamic" ErrorMessage="*"></asp:RequiredFieldValidator></td>
       </tr>
       <tr>
         <td><b>Black</b></td>
         <td><asp:DropDownList ID="blackList" runat="server"></asp:DropDownList></td>
         <td><asp:HyperLink ID="HyperLink1" runat="server" Text="Add Cartridge" NavigateUrl="~/Admin/addCartridge.aspx"></asp:HyperLink></td>
       </tr>
       <tr>
         <td><b>Color1</b></td>
         <td><asp:DropDownList ID="colorList1" runat="server"></asp:DropDownList></td>
       </tr> 
       <tr>
         <td><b>Color2</b></td>
         <td><asp:DropDownList ID="colorList2" runat="server"></asp:DropDownList></td>
       </tr>
       <tr>
         <td><b>Color3</b></td>
         <td><asp:DropDownList ID="colorList3" runat="server"></asp:DropDownList></td>
       </tr>
       <tr>
         <td><b>Other1</b></td>
         <td><asp:DropDownList ID="otherColor1" runat="server"></asp:DropDownList></td>
       </tr>
       <tr>
         <td><b>Other2</b></td>
         <td><asp:DropDownList ID="otherColor2" runat="server"></asp:DropDownList></td>
       </tr>
       <tr>
         <td><b>Other3</b></td>
         <td><asp:DropDownList ID="otherColor3" runat="server"></asp:DropDownList></td>
       </tr>
       <tr>
         <td></td>
         <td><asp:Button ID="submit" runat="server" Text="Submit" OnClick="submit_OnClick" /></td>       
       </tr>            
       <tr>
         <td></td>
         <td><asp:Label ID="submitInfo" runat="server"></asp:Label></td>       
       </tr>
      </table>
     </div>
    </ContentTemplate> 
    <Triggers>
        <asp:AsyncPostBackTrigger ControlID="submit" EventName="Click" />   
    </Triggers>   
   </asp:UpdatePanel> 
</form>

---

protected void FillTheDropDownLists()
    {
        SqlApplication con = new SqlApplication();
        try
        {
            SqlCommand cmd = new SqlCommand("SELECT name FROM BT.dbo.Cartridge ORDER BY name", con.GetConnection());
            con.OpenSqlConnection();

            SqlDataReader reader = cmd.ExecuteReader();

            blackList.DataValueField = "name";
            blackList.DataSource = reader;
            blackList.DataBind();

            colorList1.DataValueField = "name";
            colorList1.DataSource = reader;
            colorList1.DataBind();

            colorList2.DataValueField = "name";
            colorList2.DataSource = reader;
            colorList2.DataBind();

            colorList3.DataValueField = "name";
            colorList3.DataSource = reader;
            colorList3.DataBind();

            otherColor1.DataValueField = "name";
            otherColor1.DataSource = reader;
            otherColor1.DataBind();

            otherColor2.DataValueField = "name";
            otherColor2.DataSource = reader;
            otherColor2.DataBind();

            otherColor3.DataValueField = "name";
            otherColor3.DataSource = reader;
            otherColor3.DataBind();

            reader.Close();
        }
        catch (Exception err)
        {
            System.Diagnostics.Debug.WriteLine("Exception: " + err.Message);
        }
        finally
        {
            con.CloseSqlConnection();
        }
    }

Answer 1

Its becasue you are using dataReader instead of this use datatable will work for you. Reader is readonly and forward only thats why only first dropdonw get filled with data and others are empty.

changed code :

protected void FillTheDropDownLists()
    {
        SqlApplication con = new SqlApplication();
        try
        {
            SqlCommand cmd = new SqlCommand("SELECT name FROM BT.dbo.Cartridge ORDER BY name", con.GetConnection());
            con.OpenSqlConnection();

            SqlDataReader reader = cmd.ExecuteReader();
             DataTable dt = new DataTable();
            dt.Load(reader );

            blackList.DataValueField = "name";
            blackList.DataSource = dt ;
            blackList.DataBind();

            colorList1.DataValueField = "name";
            colorList1.DataSource = dt ;
            colorList1.DataBind();

            colorList2.DataValueField = "name";
            colorList2.DataSource = reader;
            colorList2.DataBind();

            colorList3.DataValueField = "name";
            colorList3.DataSource = dt ;
            colorList3.DataBind();

            otherColor1.DataValueField = "name";
            otherColor1.DataSource = dt ;
            otherColor1.DataBind();

            otherColor2.DataValueField = "name";
            otherColor2.DataSource = dt ;
            otherColor2.DataBind();

            otherColor3.DataValueField = "name";
            otherColor3.DataSource = dt ;
            otherColor3.DataBind();

            reader.Close();
        }
        catch (Exception err)
        {
            System.Diagnostics.Debug.WriteLine("Exception: " + err.Message);
        }
        finally
        {
            con.CloseSqlConnection();
        }
    }