Populate PRICE text box from selection in 2nd Dropdownlist asp.net.

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        populatemobile();
    }
}

public DataSet getdata(string sqlquery)
{
    SqlConnection con = new SqlConnection(@"server=DELL\SQLEXPRESS;Trusted_Connection=yes;Initial Catalog=product;");

    SqlDataAdapter da = new SqlDataAdapter(sqlquery, con);

    DataSet ds = new DataSet();

    da.Fill(ds);

    return ds;
}

public void populatemobile()
{
    DataSet ds = getdata("Select * from ITEM_TYPE");

    MOBDropDownList.DataSource = ds;
    MOBDropDownList.DataValueField = "TYPE_ID";
    MOBDropDownList.DataTextField = "MOBILE_NAME";
    MOBDropDownList.DataBind();

    NAMEDropDownList.Enabled = false;

    ListItem limob = new ListItem("Select MOBILE_NAME", "-1");

    MOBDropDownList.Items.Insert(0, limob);

    ListItem liname = new ListItem("Select MOBILE_TYPE", "-1");

    NAMEDropDownList.Items.Insert(0, liname);
}

protected void MOBDropDownList_SelectedIndexChanged(object sender, EventArgs e)
{
    if (MOBDropDownList.SelectedValue == "-1")
    {
        NAMEDropDownList.SelectedIndex = 0;
        NAMEDropDownList.Enabled = false;
    }
    else
    {
        NAMEDropDownList.Enabled = true;
        NAMEDropDownList.DataSource = getdata("Select * from ITEMS where MOBILE_ID = '" + MOBDropDownList.SelectedValue.ToString() + "'");
        NAMEDropDownList.DataTextField = "MOBILE_MODEL";
        NAMEDropDownList.DataValueField = "TYPE_ID";
        NAMEDropDownList.DataBind();

        ListItem liname = new ListItem("Select MOBILE_TYPE", "-1");

        NAMEDropDownList.Items.Insert(0, liname);
    }

    if (NAMEDropDownList.Enabled == true)
    {
        string str = @"server=DELL\SQLEXPRESS;Trusted_Connection=yes;Initial Catalog=product;";

        SqlConnection con = new SqlConnection(str);
        try
        {
            con.Open();

            string query = "select * from ITEMS where TYPE_ID= '" + MOBDropDownList.Text + "' ";

            SqlCommand cmd = new SqlCommand(query, con);

            SqlDataReader dbr;
            dbr = cmd.ExecuteReader();

            while (dbr.Read())
            {
                string price = dbr.GetInt32(1).ToString();
                pricetxtbox.Text = price;
            }
            con.Close();
        }      
        catch (Exception er)
        {
            MessageBox.Show(er.Message);
        }
    }
    else
    {
        string str = @"server=DELL\SQLEXPRESS;Trusted_Connection=yes;Initial Catalog=product;";

        SqlConnection con = new SqlConnection(str);
        try
        {
            con.Open();

            string query = "select * from ITEMS where MOBILE_PRICE= '" + MOBDropDownList.Text + "' ";

            SqlCommand cmd = new SqlCommand(query, con);
            SqlDataReader dbr;
            dbr = cmd.ExecuteReader();

            while (dbr.Read())
            {
                string price = dbr.GetInt32(1).ToString();
                pricetxtbox.Text = price;
            }
            con.Close();
        }
        catch (Exception er)
        {
            MessageBox.Show(er.Message);
        }
    }
}