C# Linq Enumerable 技巧

1.Datatable、DataRow[]、List 、List子集合、 某列求和

DataTable dt = new DataTable();
var sum1 = dt.Compute("SUM(Volume)", "");

DataRow[] drList = dt.Select("Name='AAA'");
var sum2 = drList.Sum(x => x.Field<decimal>("Volume"));

var tJlbList = new List<TJlb_Mod>();
var sum3 = tJlbList.Sum(o => o.FBcfs);

var sum4 = tJlbList.SelectMany(x => x.TJlb_P_Items).Sum(o => o.FBcfs);

 2.List 多属性分组

var itemList = base.ConvertToModel<Biz_Sell_ProduceshippingAdjust_Mod>(dt);
var query = itemList.GroupBy(pet => new { pet.ProduceshippingAdjustID, pet.ProduceTaskID, pet.ProduceTaskID1, pet.CancelNum, pet.DTime, pet.DTime1 });