Linq2SQL帮助转换row_number和分区

Question

有人可以帮我转换下面的t-sql到c＃linq？

select
    clientid,
    orderId 
from 
(
    select
        row_number() over (partition by clientid order by purchasedate desc) as rownum,
        clientid,
        id as orderId   
    from ordertraining
) as x where rownum = 1

Answer 1

您可以使用以下LINQ查询获得相同的结果：

from o in Orders
group o by o.clientId into g
select g.OrderByDescending(x => x.purchasedate).FirstOrDefault();

但它不会生成相同的SQL。它将使用CROSS APPLY代替。