Linq2SQL幫助轉換行號和分區

Question

有人可以幫我將以下t-sql轉換為c＃linq嗎？

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

您可以通過以下LINQ查詢獲得相同的結果：

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

但不會生成相同的SQL。 它將改為使用CROSS APPLY 。