如何从linq查询中检索聚合值

本文关键字：检索 查询 linq | 更新日期: 2023-09-27 18:28:30

我有以下查询：

from spl in SpeciesLists 
         join ar in Areas on spl.Station.Area equals ar.Id 
         join ground  in Grounds on ar.Ground equals ground.Id 
         join re in Regions on ground.Region  equals re.Id 
         where spl.Station.Trip.year ==2013
         select new 
           {
              SpciesCommonName = slp.Description,
              Are = ar.description,
              Ground = ground.Code,
              NumberOfTripsInProtectedAreas = "To be calculated",
           }

"行程"可以包括一个或多个站点。保护区域字段位于跳闸表上，可以是1或0。一个站点有一个或多个物种。

如何计算保护区内的出行次数？

提前感谢

如何从linq查询中检索聚合值

您需要在where子句中添加ProtectedArea＝＝1的条件。

此外，正如您在评论中所述，小组将通过：slp。说明、ar.Description和地代码

这是代码：

from spl in SpeciesLists 
             join ar in Areas on spl.Station.Area equals ar.Id 
             join ground  in Grounds on ar.Ground equals ground.Id 
             join re in Regions on ground.Region  equals re.Id 
             where spl.Station.Trip.year ==2013
             && spl.Station.Trip.ProtectedArea == 1
             group spl by new { slp.Description, ar.description, ground.Code } into Result
             select new 
               {
                  SpciesCommonName = Result.Key.Description,
                  Are = Result.Key.description,
                  Ground = Result.Key.Code,
                  NumberOfTripsInProtectedAreas = Result.Count()
               }
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