group by分組后對組內數據進行排序

查詢 每個班級英語成績最高的前兩名的記錄

原文：https://www.cnblogs.com/hxfcodelife/p/10226934.html

select a.Classid,a.English from
(select Classid,English,row_number() over(partition by Classid order by English desc) as n
from CJ) a
where n<=2

另外一種情況：取組內最新的數據
select max(create_time),order_id from ycej_loan_info where order_id <> '' group by order_id