Cascading dropdown box

Hello,

I need some help with my cascading dropdown boxes. Eveything works I just need to remove the duplicates from the States and Cities drop down box. Any idea how? I got it to work on the Country drop down but can't figure out the rest. Thanks.

private void FillCountry()
    {
        DataSet ds = (DataSet)Cache["InfoToFilter"];
        DataTable dt = new DataTable();

        ds = GetInfoFromDB2();

        dt = ds.Tables[0];
        foreach (DataRow dr in dt.Rows)
        {
            dr["country"] = AsciiToString(dr["country"].ToString());
        }
        dt.AcceptChanges();


        //Populate the list of categories     
        lstPublisher.DataSource = dt;
        lstPublisher.DataValueField = "country";
        lstPublisher.DataTextField = "country";
        lstPublisher.DataBind();
        lstPublisher.Items.Insert(0, "--Select--");
        lstAuthor.Enabled = false;
        lstTitle.Enabled = false;


    }


    /*###########################################################################################*/
    private void FillStates(string countryID)
    {
        DataSet ds = (DataSet)Cache["InfoToFilter"];
        ds = GetInfoFromDB();

        DataTable dt = ds.Tables[0];
        foreach (DataRow dr in dt.Rows)
        {
            dr["country"] = AsciiToString(dr["country"].ToString());
            dr["states"] = AsciiToString(dr["states"].ToString());

        }
        dt.AcceptChanges();

        DataView view = new DataView();
        view.Table = ds.Tables[0];
        
        string filter = String.Format("country LIKE '{0}'", EscapeLikeValue(countryID));
        view.RowFilter = filter;

        //Populate the list of categories     
        lstAuthor.DataSource = view;
        lstAuthor.DataValueField = "ID";
        lstAuthor.DataTextField = "states";
        lstAuthor.DataBind();
        lstAuthor.Items.Insert(0, "--Select--");
    }


    /*###########################################################################################*/
    private void FillCities(string statesID)
    {
        DataSet ds = (DataSet)Cache["InfoToFilter"];
        ds = GetInfoFromDB();
        DataTable dt = ds.Tables[0];
        foreach (DataRow dr in dt.Rows)
        {
            dr["cities"] = AsciiToString(dr["cities"].ToString());
            dr["states"] = AsciiToString(dr["states"].ToString());

        }
        dt.AcceptChanges();
        DataView view = new DataView();
        view.Table = ds.Tables[0];
        
        string filter = String.Format("states LIKE '{0}'", EscapeLikeValue(statesID));
        view.RowFilter = filter;
        //Populate the list of categories      
        lstTitle.DataSource = view;
        lstTitle.DataValueField = "ID";
        lstTitle.DataTextField = "cities";
        lstTitle.DataBind();
        lstTitle.Items.Insert(0, "--Select--");

    }



 /*###########################################################################################*/
    private DataSet GetInfoFromDB()
    {
        //Read the connection string from Web.config
        string connectionString = ConfigurationManager.ConnectionStrings["Application"].ConnectionString;
        OleDbDataAdapter adp = new OleDbDataAdapter("SELECT Id, country, states, cities FROM myTable", connectionString);
        DataSet ds = new DataSet();
        adp.Fill(ds);

        return ds;
    }

    /*###########################################################################################*/
    private DataSet GetInfoFromDB2()
    {
        //Read the connection string from Web.config
        string connectionString = ConfigurationManager.ConnectionStrings["Application"].ConnectionString;
        OleDbDataAdapter adp = new OleDbDataAdapter("SELECT DISTINCT country FROM myTable", connectionString);
        DataSet ds = new DataSet();
        adp.Fill(ds);

        return ds;
    }