public void insert_Bill(string bill_ID, string room_ID, string customer_ID, string month, double service_money)
{
string sql = " insert into bill values('" + bill_ID + "','" + room_ID + "','" + customer_ID + "','" + month + "'," + service_money + ")";
da.ExcuteNonQuery(sql);
}
public void insert_Room(string room_ID, string type_room, int number_floor, double price, string status_room, int number_person)
{
string sql = " insert into Room values('" + room_ID + "','" + type_room + "'," + number_floor + "," + price + ",'" + status_room + "'," + number_person + ")";
da.ExcuteNonQuery(sql);
}