SELECT TOP 1000 [id] 
        ,[ad] 
    FROM [cls].[dbo].[il] 
  

  SELECT TOP 1000 [id] 
        ,[il_id] 
        ,[ad] 
    FROM [cls].[dbo].[ilce]

 
  using System; 
  using System.Collections.Generic; 
  using System.Linq; 
  using System.Web; 
  using System.Web.UI; 
  using System.Web.UI.WebControls; 
  using System.Data; 
  using System.Data.SqlClient; 
  using System.Configuration; 
   
  namespace WebApplication2 
  { 
      public partial class WebForm1 : System.Web.UI.Page 
      { 
          protected void Page_Load(object sender, EventArgs e) 
          { 
              if (!IsPostBack) 
              { 
                  string constr = ConfigurationManager.ConnectionStrings["BayiSecim"].ConnectionString; 
                  SqlConnection sql = new SqlConnection(constr); 
                  SqlCommand com = new SqlCommand("Select * from il", sql); 
   
                  try 
                  { 
                      sql.Open(); 
                      SqlDataReader reader = com.ExecuteReader(); 
   
                      DropDownList1.DataSource = reader; 
                      DropDownList1.DataTextField = "ad"; 
                      DropDownList1.DataValueField = "id"; 
                      DropDownList1.DataBind(); 
                      reader.Close(); 
                  } 
   
                  catch 
                  { 
                      Response.Write("Bir hata oluştu"); 
                  } 
   
                  sql.Close(); 
   
   
              } 
          } 
   
          protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e) 
          { 
              string constr = ConfigurationManager.ConnectionStrings["BayiSecim"].ConnectionString; 
              SqlConnection sql = new SqlConnection(constr); 
              SqlCommand com = new SqlCommand(" SELECT il.ad, ilce.ad FROM il, ilce WHERE il.id = ilce.il_id = " + DropDownList1.SelectedItem.Value, sql); 
   
              try 
              { 
                  sql.Open(); 
   
                  SqlDataReader reader = com.ExecuteReader(); 
   
                  DropDownList2.DataSource = reader; 
                  DropDownList2.DataTextField = "ad"; 
                  DropDownList2.DataValueField = "id"; 
                  DropDownList2.DataBind(); 
                  reader.Close(); 
              } 
   
              catch 
              { 
                  Response.Write("Bir hata oluştu"); 
              } 
   
              sql.Close(); 
          } 
          } 
  }