c# - LINQ查询分组并求和

我有以下查询，它连接了由StationId连接的RailwayStation对象和ExpenditureData对象的集合，我试图获取前10个StationCargoCodes（Station对象上的一个属性），并且还为前10个对象选择了ExpenditureCost的总和，但是我无法获取正确的语法：

var data = (from s in stations join e in expenditureData on s.stationId
equals e.StationId
orderby e.expenditureAmount descending
select s)
.Sum(e => e.expenditureAmount)
.GroupBy(n => n.StationCargoCode)
.Take(10);

为此，我需要什么LINQ进行分组和求和？

最佳答案

var query = from s in stations
            join e in expenditureData
                on s.stationId equals e.StationId into se
            group se by new
            {
                s.StationCargoCode, ExpenditureCostSum = se.Sum(x => x.ExpenditureCost)
            } into g
            orderby g.Key.ExpenditureCostSum descending
            select g.Key;

var top10 = query.Take(10).ToList();

关于c# - LINQ查询分组并求和，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/43621878/

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c# - LINQ查询分组并求和