Linq 数据操作

1.数据筛除重复的（就是剩下的都是不重复的）

list.GroupBy(x => new { x.aid, x.name }).Select(x => x.First()); 

 2.Where条件下查询两个字段

var doorBy = door.Where(x => x.f_DoorID == p.f_DoorID).Select(x => new { x.f_DoorNO, x.f_ControllerID });

 3.多表联合查询组成一个新结果集

　　　　　　　　　　　　　　　　var doorBy = (from x in door
                                  join y in consumer on p.f_ConsumerID equals y.f_ConsumerID
                                  join z in device on p.f_ControllerID equals z.f_ControllerID
                                  where x.f_DoorID == p.f_DoorID
                                  select new
                                  {
                                      x.f_ControllerID,
                                      x.f_DoorNO,
                                      y.f_CardNO,
                                      z.F_ControllerSN,
                                  }).First();

.First()表示第一条记录。

4.Group By 分组

var PeopleCard = from x in doo group x.Card by new { x.Card, x.SN } into g select g;

 

5.查询价格在100元以下的前10条记录，并且按价格从低到高显示

 return View(repository.Books
                .OrderBy(b=>b.Price)
                .Where(b=>b.Price<100)
                .Take(10));