C#后台的一些常用的公用方法--Linq篇

        项目中使用到的linq写法记录。

var groups_Cost_FirstTitle = (
                                 from p in list_COST_CEN_Summary_Structures
                                 where p.COST_CEN_GRP == "OPEX2019"
                                 group p by new
                                 {
                                     p.SUB_COST_CEN_GRP,
                                     p.SUB_COST_CEN_GRP_NAME
                                 }
                                 into q
                                 select q.Key
                              ).ToList();

var groups_First_CostCenID 
            = (
                    from p in list_COST_CEN_Summary_Structures
                    where p.COST_CEN_GRP == "OPEX2019"
                    && p.SUB_COST_CEN_GRP == list_COST_CEN_AREA_ONE[a].COST_CEN_AREA_ONE_ID
                    group p by p.COST_CEN_ID
                    into q
                    select q.Key
               ).ToList();