three tier architecture

Question

i use a registration form in that based on one ddl1 it generate another ddl2

 

my problem is i using these in three tier architecture i dont know how to bind the ddl2 based on ddl1 .selectedvalue

 

 

here is my code     1.DAL.cs,   2.BAL.cs     3.registration form .cs  

 

ddl ID="ddlstate"

 

 

1.DAL.cs 

public DataTable Bind_ddlCity()

{

try

{

con = new SqlConnection(s);

con.Open();

string qry = "select state, from cntryandstate where cntry ='" + dd + "'";

cmd = new SqlCommand(qry, con);

SqlDataAdapter da = new SqlDataAdapter(cmd);

DataTable dt = new DataTable();

da.Fill(dt);

return dt;

}

catch

{

throw;

}

finally

{

cmd.Dispose();

con.Close();

con.Dispose();

}

}

 

 2.BAL.Cs

 

public DataTable Bind_ddlCity()

{

try

{

return obj.Bind_ddlCity();

}

catch

{

throw;

}

finally

{

//obj = null;

}

}

 

 

3 .registration form .cs

 

private void Bind_ddlCity()

{

DataTable ret;

ret = obj.Bind_ddlCity();

if (ret.Rows.Count != 0)

{

ddlstate.DataSource = ret;

ddlstate.DataTextField = "state";

ddlstate.DataValueField = "cntry";

ddlstate.DataBind();

}