Disable selection of ListItem in ASP.Net DropDownList

Here i have used Dummy table to create one sample.

HTML

<asp:DropDownList ID="ddlBuilders" runat="server">
</asp:DropDownList>

Namespace

using System.Data;

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        DataTable dtBuliders = new DataTable();
        dtBuliders.Columns.AddRange(new DataColumn[2] { new DataColumn("ID", typeof(int)),
                                            new DataColumn("Name", typeof(string )) });
        dtBuliders.Rows.Add(1, "Nancy Davolio");
        dtBuliders.Rows.Add(2, "Andrew Fuller");
        dtBuliders.Rows.Add(3, "Janet Leverling");
        dtBuliders.Rows.Add(4, "Anne Dodsworth");
        dtBuliders.Rows.Add(5, "Steven Buchanan");
        dtBuliders.Rows.Add(6, "Michael Suyama");
        dtBuliders.Rows.Add(7, "Robert King");
        dtBuliders.Rows.Add(8, "Laura Callahan");
        this.ddlBuilders.DataValueField = "ID";
        this.ddlBuilders.DataTextField = "Name";
        this.ddlBuilders.DataSource = dtBuliders;
        this.ddlBuilders.DataBind();

        DataTable dtProjects = new DataTable();
        dtProjects.Columns.AddRange(new DataColumn[3] { new DataColumn("ID", typeof(int)),
                                                    new DataColumn("BuilderName", typeof(int)),
                                            new DataColumn("ProjectName", typeof(string )) });
        dtProjects.Rows.Add(1, 1, "Abc");
        dtProjects.Rows.Add(1, 3, "PQR");
        dtProjects.Rows.Add(1, 4, "XYZ");
        foreach (DataRow row in dtProjects.Rows)
        {
            this.ddlBuilders.Items.FindByValue(row["BuilderName"].ToString()).Attributes["disabled"] = "disabled";
        }
    }
}

Screenshot

Incredible Efforts My Friend AZIM , I appreciate your EFFORTS !! however this trick helped me ...

    private void DisableSelectedBuilders()
    {

     try
        {
            string projId = null;
            foreach (DataListItem item in myDataList.Items)
            {
                projId = ((Label)(item.FindControl("ProjID"))).Text;
            }
            string query = "SELECT [builder_id] FROM [dbo].[d_pprofile_bld] WHERE [is_deleted] IS NULL AND [project_id] = " + int.Parse(projId) + "";
            var comm = new SqlCommand(query, _connection);
            _connection.Open();
            var dt = new DataTable();
            var da = new SqlDataAdapter { SelectCommand = comm };
            da.Fill(dt);
            foreach (DataRow row in dt.Rows)
            {
                BuilderAssignDropDwn.Items.FindByValue(row["builder_id"].ToString()).Attributes.Add("Disabled", "Disabled");
                BuilderAssignDropDwn.Items.FindByValue(row["builder_id"].ToString()).Attributes.Add("style", "background:#eee");
                BuilderAssignDropDwn.Items.FindByValue(row["builder_id"].ToString()).Text += "  (Already Assigned)";
                BATTP_UPanel.Update();
            }
            _connection.Close();
        }
        catch (Exception)
        {
            
            
        }
    }