Заполнение combobox из БД

    private void comboBox2_SelectedIndexChanged(object sender, EventArgs e)
        {
 
            string connectString = @"Data Source =(LocalDB)\MSSQLLocalDB;AttachDbFilename=C:\Users\max\Documents\Visual Studio 2015\Projects\ЭАТ\ЭАТ\Database.mdf;Initial Catalog=UTT;" + "Integrated Security = true;";
 
            SqlConnection myConnection = new SqlConnection(connectString);
 
            myConnection.Open();
 
            string query = "SELECT * FROM UTT WHERE type = 'kran'";
 
            DataTable ds = new DataTable();
            SqlCommand cmd1 = new SqlCommand(query, myConnection);
            cmd1.Connection = myConnection;
            SqlDataReader UTT = cmd1.ExecuteReader();
            ds.Load(UTT);
            
            comboBox2.DataSource = ds;
            comboBox2.DisplayMember = "auto";
            comboBox2.ValueMember = "type";
 
            myConnection.Close();
                                 
        }

comboBox1.DataSource = ds.DefaultView;

 UTT.Fill(ds);

 private void LoadData1()
        {
 
            string connectString = @"Data Source =(LocalDB)\MSSQLLocalDB;AttachDbFilename=C:\Users\max\Documents\Visual Studio 2015\Projects\ЭАТ\ЭАТ\Database.mdf;Initial Catalog=UTT;" + "Integrated Security = true;";
 
            SqlConnection myConnection = new SqlConnection(connectString);
 
            myConnection.Open();
 
            string query = "SELECT auto FROM UTT ORDER BY type";
 
            SqlCommand cmd1 = new SqlCommand(query, myConnection);
            DataTable tbl1 = new DataTable();
            SqlDataAdapter da = new SqlDataAdapter(cmd1);
            da.Fill(tbl1);
 
            myConnection.Close();
 
            if (comboBox1.SelectedItem == "kran")
            {
                this.comboBox2.DataSource = tbl1;
                this.comboBox2.DisplayMember = "auto";
                this.comboBox2.ValueMember = "type";
 
            }
        }