protected void Page_Load(object sender, EventArgs e)
 {
     if (!IsPostBack)
     {
         if (con.State == ConnectionState.Closed)
         {
             con.Open();
         }
         SqlCommand sqlcmd1 = new SqlCommand("select make from cars  ", con);
         DropDownMake.DataSource = sqlcmd1.ExecuteReader();
         DropDownMake.DataBind();
         con.Close();
         if (con.State == ConnectionState.Closed)
         {
             con.Open();
         }
         SqlCommand sqlcmd2 = new SqlCommand("select model from cars  ", con);
         DropDownModel.DataSource = sqlcmd2.ExecuteReader();
         DropDownModel.DataBind();
         con.Close();
         if (con.State == ConnectionState.Closed)
         {
             con.Open();
         }
         SqlCommand sqlcmd3 = new SqlCommand("select style from cars  ", con);
         DropDownStyle.DataSource = sqlcmd3.ExecuteReader();
         DropDownStyle.DataBind();
         con.Close();
         con.Close();
         if (con.State == ConnectionState.Closed)
         {
             con.Open();
         }
         SqlCommand sqlcmd4 = new SqlCommand("select year from cars  ", con);
         DropDownYear.DataSource = sqlcmd4.ExecuteReader();
         DropDownYear.DataBind();
         con.Close();
     }
 }