private void Hostel_select_Load(object sender, EventArgs e)
        {
            ORMDataContext a1    = new ORMDataContext();
            Hostel_find    h1    = new Hostel_find();
            var            query = from Hostel_find in a1.Hostel_finds
                                   where Hostel_find.A_name == sel
                                   select Hostel_find.H_name;

            comboBox1.ValueMember   = "H_name";
            comboBox1.DisplayMember = "H_name";
            comboBox1.DataSource    = query;

            var query1 = from Cost_info in a1.Cost_infos
                         where Cost_info.name == comboBox1.SelectedItem.ToString()
                         select Cost_info;

            dataGridView1.DataSource = query1;
        }
 partial void DeleteHostel_find(Hostel_find instance);
 partial void UpdateHostel_find(Hostel_find instance);
 partial void InsertHostel_find(Hostel_find instance);