Web由于 IGrouping 实现了 IEnumerable ，因此您可以使用 SelectMany 将所有 IEnumerables 放回一个 IEnumerable 中： List list = new …

IGrouping on multiple columns - social.msdn.microsoft.com

Web'IEnumerable < IGrouping< string, DataRow > >' does not contain a definition for 'ToList' You basically are trying to put a complex object into a string: IGrouping myGrouping = null; string s = myGrouping; // This won't work You have to Select what strings you want to see in your List: Web25 okt. 2015 · 一、接口IEnumerable实现 1、建一个学生数据结构和一个学生集合类： //student数据结构 class Student { public int id; public string name; } //student 集合 … how to order costco cupcakes

如何从IGrouping获取值 - 问答 - 腾讯云开发者社区-腾讯云

Web28 sep. 2007 · 1. 2. IEnumerable> grouped =. data.GroupBy (record => record.Type); And then things become a little more obvious. We get back an enumeration of IGrouping. Now, IGrouping looks like this; so an IGrouping essentially has a Key property of type K and it also implements … Web14 dec. 2011 · IEnumerable> groups = list.GroupBy (x => x.ID) foreach (IEnumerable element in groups) { //do something } Google shows … Web23 aug. 2012 · C# 使用DataTable的GroupBy,对数据某列进行分组求和一、需求背景二、使用DataTable创建表及数据三、GroupBy对数据分组求和 一、需求背景 通过Data Table创建多个行，根据MaterialID进行Group By分组，对Qty进行求和运算.原始数据 Material TotalQTY Qty A 10 1 B 20 1 B 20 2 A 10 3 要获得的数据 Material TotalQTY Qty A 10 4 B how to order countryfile calendar by post