Linq多级分组

Question

我正在尝试在linq中实现多级分组

在sql中就是这样的。

Select VarId, variable, UT , 
       (case when resultat >= 0 then sum(resultat) else 0) as Positive,
       (case when resultat < 0 then sum(resultat) else 0) as Negatif
from 
      (Select VarId, variable, UT , valeur, sum( resultat ) from IndicRow 
             group by VarId, variable, UT , valeur)
group by VarId, variable, UT 

我已经在linq中创建了但是我找不到按组分组的方法

var Chartline = from IndicRow in Indic_dt.AsEnumerable()
                            //where SelTradeId.Contains(IndicRow.Field<int>("TradeNum"))
                            group IndicRow by new
                            {
                                GpVariable = IndicRow.Field<string>("Variable"),
                                GpUT = IndicRow.Field<string>("UT"),
                                GPVarId = IndicRow.Field<int>("VarId"),
                                GPValue = IndicRow.Field<double>("Valeur")
                            } into RdVal
                            select new
                            {
                                VarId = RdVal.Key.GPVarId,
                                Variable = RdVal.Key.GpVariable,
                                UT = RdVal.Key.GpUT,
                                Valeur = RdVal.Key.GPValue,
                                Resultat = RdVal.Sum(IndicRow => IndicRow.Field<double>("Resultat_EuroNet"))
                            };

最终目标是获得5列数据表（VarId，变量，UT，正数，负数）

Answer 1

两级分组的一般模式是

from t in Mains
group t by t.GroupProperty1 into mainGroup
select new { mainGroup.Key,
             MainCount = mainGroup.Count(), 
             subGroups = from mg in mainGroup
                         group mg by mg.GroupProperty2 into subGroup
                         select new { subGroup.Key,
                                      SubCount = subGroup.Count()
                                    }
           }

因此，主要分组由VarId, variable, UT和子分组仅由valeur组成，因为子组仅包含一个主要组的项目。