是否有可能是不存在的GROUPBY列订购？ [英] Is it possible to order by column which is not present in groupby?

问题描述

例如，我有这样的查询：

For example , i have a query like this:

var data= from c in customers
          join o in orders
          on c.id=o.id
         group new { c, o } by new { o.customerid, c.FirstName, c.LastName, c.City } into customergroups
         orderby customergroup.select(x=>x.o.quantity)

但是， ..

请建议...

推荐答案

可以按任何顺序对组进行排序，只要表达式产生一个可比较的对象。例如，您可以按最小或最大数量 ^* 进行排序，但不能只按数量排序，因为可能有许多不同的数量

Yes, it is possible to order your groups by anything, as long as the expression produces a comparable object. For example, you could order by the minimum or the maximum quantity ^*, but not by just quantity, because there may be many different quantities in a group.

var data= from c in customers
      join o in orders
      on c.id=o.id
     group new { c, o } by new { o.customerid, c.FirstName, c.LastName, c.City } into customergroups
     orderby customergroup.Max(x=>x.o.quantity);

^* 您也可以使用 => xoquantity）或 Last（x => xoquantity），但顺序是任意的。

^* You could also use First(x=>x.o.quantity) or Last(x=>x.o.quantity), but the order would be arbitrary.

这篇关于是否有可能是不存在的GROUPBY列订购？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！