asp.net MVC + EF , ?Linq的基本用法

 public ActionResult Index() ???????{ ???????????NewsEntities news = new NewsEntities(); ???????????//select * from NewsInfo ???????????#region 排序 ???????????var query = from s in news.NewsInfo ???????????????????????orderby s.ID descending ??//ascending ???????????????????????select new { id = s.ID, name = s.Name, auter = s.Auter }; ??//构造属性 ???????????foreach (var item in query) ???????????{ ???????????????int id = item.id; ???????????????string name = item.name; ???????????} ???????????#endregion ???????????#region where条件 ?+ top ???????????//var query1 = from s in news.NewsInfo ???????????// ???????????where s.ID >= 1 && s.ID <= 6 ???????????// ???????????select s; ???????????var query1 = (from s in news.NewsInfo ?????????????????????????where s.Name.StartsWith("啊") ?//EndsWith : ?name like ‘%啊‘ ,Contains : name like ‘%啊%‘ , StartsWith : name like ‘啊%‘ ?????????????????????????select s).Take(3); ??//take() 类似top ???????????foreach (var item in query1) ???????????{ ???????????????int id = item.ID; ???????????????string name = item.Name; ???????????} ???????????#endregion ???????????#region 函数 ???????????var query2 = from s in news.NewsInfo ????????????????????????group s by new { s.ID, s.Time } into tab ????????????????????????select tab; ???????????//int? sum = query3.Sum(f => f.Key.ID); ???????????//System.DateTime? maxid = query3.Max(f => f.Key.Time); ???????????foreach (var item in query2) ???????????{ ???????????????var id = item.Key.ID; ???????????????var time = item.Key.Time; ???????????????//统计一组数据记录数 ???????????????int count = item.Count(); ???????????????//计算一组的平均ID ???????????????double? avg = item.Average(f => f.ID); ???????????????//计算ID之和 ???????????????int? sum = item.Sum(f => f.ID); ???????????????//统计当前最大 最小的ID数 ???????????????int? maxid = item.Max(f => f.ID); ???????????????int? minid = item.Min(f => f.ID); ???????????} ???????????#endregion ???????????#region ?skip(跳过指定前几行) + take(再获取前几行) ???????????var query3 = (from s in news.NewsInfo ?????????????????????????orderby s.ID ascending ?????????????????????????select s).Skip(2).Take(3); ??//take() 类似top ???????????foreach (var item in query3) ???????????{ ???????????????int id = item.ID; ???????????????string name = item.Name; ???????????} ???????????#endregion ???????????#region linq 分页操作 ???????????//当前页码 ???????????int pageindex = 1; ???????????//每页数量 ???????????int pagesize = 2; ???????????var list = (from s in news.NewsInfo ???????????????????????orderby s.ID ascending ???????????????????????select s).Skip((pageindex - 1) * pagesize).Take(pagesize); ???????????#endregion ???????????#region ?链表查询(查询数据里的所有男女性别 并输出男女性别数量) ???????????var list1 = from ss in ???????????????????????????( ???????????????????????????????from s in news.NewsInfo ???????????????????????????????join g in news.GTable on s.ID equals g.ID ???????????????????????????????select new ???????????????????????????????{ ???????????????????????????????????id = s.ID, ???????????????????????????????????name = s.Name, ???????????????????????????????????gsex = g.Sex ???????????????????????????????} ???????????????????????????) ???????????????????????group ss by ss.gsex into tab ???????????????????????select tab; ???????????foreach (var item in list1) ???????????{ ???????????????var Class = item.Key; ???????????????var count = item.Count(); ???????????} ???????????#endregion ???????????#region ?子表查询(用b表的ID查询a表的name列) ???????????var zi = from b in news.GTable ????????????????????select new ????????????????????{ ????????????????????????id = b.ID, ????????????????????????name = ( ????????????????????????????from a in news.NewsInfo ????????????????????????????where b.ID == a.ID ????????????????????????????select a.Name ????????????????????????).FirstOrDefault() ????????????????????}; ???????????foreach (var item in zi) ???????????{ ???????????????var name = item.id; ???????????????var gname = item.name; ???????????} ???????????#endregion ???????????return View(); ???????}