/// <summary>

        /// 根据条件排序和查询

        /// </summary>

        /// <typeparam name="TKey">排序字段类型</typeparam>

        /// <param name="whereLambda">查询条件 lambda表达式</param>

        /// <param name="orderLambda">排序条件 lambda表达式</param>

        /// <returns></returns>

        public static  IEnumerable<Customers> GetListBy<TKey>(Expression<Func<Customers, bool>> whereLambda, Expression<Func<Customers, TKey>> orderLambda)

        {

            using (NorthwindEntities db = new NorthwindEntities())

            {

                return db.Customers.Where(whereLambda).OrderBy(orderLambda).ToList();

            }

        }

 /// <summary>

        /// 分页查询

        /// </summary>

        /// <param name="pageIndex">页码</param>

        /// <param name="pageSize">页容量</param>

        /// <param name="whereLambda">条件 lambda表达式</param>

        /// <param name="orderBy">排序 lambda表达式</param>

        /// <returns></returns>

        public static List<Customers> GetPagedList<TKey>(int pageIndex, int pageSize, Expression<Func<Customers, bool>> whereLambda,

                    Expression<Func<Customers, TKey>> orderBy)

        {

            using (NorthwindEntities db = new NorthwindEntities())

            {

                // 分页时一定注意： Skip 之前一定要 OrderBy

                return db.Customers.Where(whereLambda).OrderBy(orderBy).Skip((pageIndex - 1) * pageSize).Take(pageSize).ToList();

            }

        }

 var a = GetListBy<string>((p)=> p.CustomerID == "11", (q) => q.ContactName);

  IQueryable<Orders> or = db.Orders.Where(u=>u.CustomerID=="11").Take(1);

                List<Orders> aa = or.ToList();