const int PAGE_SZ = 10;[Route("{id:int}/{page:int=1}")]public ActionResult Index(int? id, int? page){var articles = (id == null || id == 0) ? _db.Articles : _db.Articles.Where    (art => art.CatalogId == id);var recordCount = articles.Count();articles = articles.OrderByDescending(art => art.EditTime). Skip((page.Value - 1) * PAGE_SZ).Take(PAGE_SZ);ViewBag.Pager = new Pager(){PageIndex = page.Value,PageSize = PAGE_SZ,RecordCount = recordCount,};return View(articles);
}        

        /// <summary>/// 根据指定的集合表达式和排序字段得出一个分页对象和分页后的数据集/// </summary>/// <typeparam name="T">实体的类型</typeparam>/// <typeparam name="TSort">用于排序的属性类型</typeparam>/// <param name="allList">初始的集合</param>/// <param name="orderExpress">排序的表达式</param>/// <param name="page">页号</param>/// <param name="pageSize">页数</param>/// <returns></returns>public static Pager GetPagedList<T, TSort>(ref IQueryable<T> allList,Expression<Func<T, TSort>> orderExpress, int? page, int pageSize = 20){int p = Math.Max(1, page == null ? 1 : page.Value);var recordCount = allList.Count();allList = allList.OrderByDescending(orderExpress).Skip((p - 1) * pageSize).Take(pageSize);return new Pager(){PageIndex = p,PageSize = pageSize,RecordCount = recordCount,};}

        public ActionResult Index(int? id, int? page){var articles = (id == null || id == 0) ? _db.Articles : _db.Articles.Where(art => art.CatalogId == id);
//此方法要返回两个值，一个是分页对象，一个是分页后的集合。所以后者用ref传地址。 art=>art.Id是表示根据Id排序.            ViewBag.Pager = Pager.GetPagedList(ref articles, art => art.Id, page);return View(articles);}

SELECT [GroupBy1].[A1] AS [C1]FROM ( SELECT COUNT(1) AS [A1]FROM [dbo].[CT_Article] AS [Extent1])  AS [GroupBy1]SELECT TOP (20) [Extent1].[Id] AS [Id], [Extent1].[ParentId] AS [ParentId], [Extent1].[Title] AS [Title], [Extent1].[Text] AS [Text], [Extent1].[Intro] AS [Intro], [Extent1].[CatalogId] AS [CatalogId], [Extent1].[AuthorId] AS [AuthorId], [Extent1].[ReplyCount] AS [ReplyCount], [Extent1].[HitCount] AS [HitCount], [Extent1].[PostTime] AS [PostTime], [Extent1].[LastReplyTime] AS [LastReplyTime], [Extent1].[Status] AS [Status]FROM ( SELECT [Extent1].[Id] AS [Id], [Extent1].[ParentId] AS [ParentId], [Extent1].[Title] AS [Title], [Extent1].[Text] AS [Text], [Extent1].[Intro] AS [Intro], [Extent1].[CatalogId] AS [CatalogId], [Extent1].[AuthorId] AS [AuthorId], [Extent1].[ReplyCount] AS [ReplyCount], [Extent1].[HitCount] AS [HitCount], [Extent1].[PostTime] AS [PostTime], [Extent1].[LastReplyTime] AS [LastReplyTime], [Extent1].[Status] AS [Status], row_number() OVER (ORDER BY [Extent1].[Id] DESC) AS [row_number]FROM [dbo].[CT_Article] AS [Extent1])  AS [Extent1]WHERE [Extent1].[row_number] > 0ORDER BY [Extent1].[Id] DESC