public List <BanBEAN> themBan(List <BanBEAN> ds, string maBan, string tenBan, long soGhe, out Boolean kq)
        {
            kq = false;
            // lấy về tất cả các loại có mã  là maLoai
            var q = from l in ds
                    where l.MaBan.Equals(maBan)
                    select l;

            if (q.Count() == 0)
            {
                // thêm csdl
                ban.themBan(maBan, tenBan, soGhe);
                // thêm bộ nhớ
                BanBEAN b = new BanBEAN(maBan, tenBan, soGhe);
                ds.Add(b);
                kq = true;
            }
            return(ds);
        }
        public List <BanBEAN> timBan(string key)
        {
            string       sql = "SELECT * FROM Ban WHERE TenBan LIKE @tenBan ";
            SqlCommand   cmd = new SqlCommand(sql, DungChung.cn);
            SqlParameter ts  = new SqlParameter("@tenBan", "%" + key + "%");

            cmd.Parameters.Add(ts);
            SqlDataReader  rs = cmd.ExecuteReader();
            List <BanBEAN> ds = new List <BanBEAN>();

            while (rs.Read())
            {
                string  maBan  = rs["MaBan"].ToString();
                string  tenBan = rs["TenBan"].ToString();
                string  soGhe  = rs["SoGhe"].ToString();
                BanBEAN ban    = new BanBEAN(maBan, tenBan, long.Parse(soGhe));
                ds.Add(ban);
            }
            rs.Close();
            return(ds);
        }
        public List <BanBEAN> getListBan()
        {
            string         sql = "SELECT * FROM Ban";
            SqlCommand     cmd = new SqlCommand(sql, DungChung.cn);
            SqlDataReader  rs  = cmd.ExecuteReader();
            List <BanBEAN> ds  = new List <BanBEAN>();

            while (rs.Read())
            {
                string  maBan  = rs["MaBan"].ToString();
                string  tenBan = rs["TenBan"].ToString();
                string  soGhe  = rs["SoGhe"].ToString();
                BanBEAN ban    = new BanBEAN(maBan, tenBan, long.Parse(soGhe));
                ds.Add(ban);

                //String[] st = new String[2];
                //st[0] = rs[0].ToString();
                //st[1] = rs[1].ToString();
            }
            rs.Close();
            return(ds);
        }