sql 求和后分组 再取每组最大值

WITH A as(SELECt max(a.ordernum) as ordernum,a.orderyear
FROM
(SELECt count(*) as ordernum,EXTRACT (year from orderdate) as orderyear,customerid
FROM orders
GROUP BY orderyear,customerid) a
GROUP BY a.orderyear)

SELECt COUNT(*) as ordernum,EXTRACT (year from orderdate) orderyear,customerid
FROM orders o
GROUP BY orderyear,customerid
HAVINg COUNT(*)=(select ordernum FROM A )
ORDER BY orderyear DESC

跑出来ERROR: more than one row returned by a subquery used as an expression
我感觉是having 条件句有问题
但是不知道怎么改
谢谢！

不知道你这怎么样才算第一个先用一个rownum列出每一个值的序号，再在外面去取每组的序号为1和最大的那个，并关联求出值来吧

select max(时刻值) ,min(时刻值) from (select 日期 时刻 名称 类型 等级 sum(时刻值) from to group by 日期 时刻 名称 类型 等级)