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

1 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

 1 　　　　　　　　　　　　　　　　var doorBy = (from x in door
 2                                   join y in consumer on p.f_ConsumerID equals y.f_ConsumerID
 3                                   join z in device on p.f_ControllerID equals z.f_ControllerID
 4                                   where x.f_DoorID == p.f_DoorID
 5                                   select new
 6                                   {
 7                                       x.f_ControllerID,
 8                                       x.f_DoorNO,
 9                                       y.f_CardNO,
10                                       z.F_ControllerSN,
11                                   }).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

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