Fatch data from database to Checkbox List ON Select

Question

I have 3 levels of selection.
In the first level have to disply all the Country in a check box list from the database.
The user is allowed to select any number of Countries and based on those selections
I have to show the States which comes under each Countries in seperate checkbox lists.
The user is allowed to select any number of States and based on these selections
I have to show the disttric of each selected States.

please help to solve it.

 i am using following code but its not work proper 

 

MySqlConnection con;

con = new MySqlConnection(ConfigurationManager.ConnectionStrings["con"].ToString());

con.Open();

try

{

for (int i = 0; i < CblistForPravilage.Items.Count; i++)

{

if (CblistForPravilage.Items[i].Selected)

{

string var = string.Empty;

var += CblistForPravilage.Items[i].Value.ToString();

string str = "SELECT * FROM add_state where CID='" + var + "'";

MySqlCommand cmd;

cmd = new MySqlCommand(str, con);

MySqlDataAdapter da = new MySqlDataAdapter(cmd);

DataSet ds = new DataSet();

da.Fill(ds);

if (ds.Tables[0].Rows.Count > 0)

{

CblistForPravilage0.DataSource = ds;

CblistForPravilage0.DataTextField = "SName";

CblistForPravilage0.DataValueField = "SID";

CblistForPravilage0.DataBind();

}

}

}

}

catch

{

}

}