C# LINQ Group By Multiple fields - 语法帮助
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LINQ Group By Multiple fields -Syntax help
提问by Udana
What is the correction needed for example 2inorder to group by multiple columns
例如 2需要什么更正才能按多列分组
Example 1
示例 1
var query = from cm in cust
group cm by new { cm.Customer, cm.OrderDate } into cms
select
new
{ Key1 = cms.Key.Customer,Key2=cms.Key.OrderDate,Count=cms.Count() };
Example 2 (incorrect)
例2（错误）
var qry =
cust.GroupBy(p => p.Customer, q => q.OrderDate, (k1, k2, group) =>
new { Key1 = k1, Key2 = k2, Count = group.Count() });
采纳答案by Jon Skeet
Use the same anonymous type in the dot notation that you do in the query expression:
在点表示法中使用与查询表达式中相同的匿名类型：
var qry = cust.GroupBy(cm => new { cm.Customer, cm.OrderDate },
(key, group) => new { Key1 = key.Customer, Key2 = key.OrderDate,
Count = group.Count() });
(In a real IDE I'd have (key, group)lined up under the cmparameter, but then it would wrap in SO.)
（在一个真正的 IDE 中，我会(key, group)在cm参数下排列，但它会包装在 SO 中。）
