让我看到你们的答案，加油

-- SQL SERVER 数据库
select top 5 client_id,sum(amount) amount from sell_book where date between '2021-09-01 00:00:00' and '2021-09-30 23:59:59' group by client_id order by amount desc

--mysql 数据库
select client_id,sum(amount) amount from sell_book where date between '2021-09-01 00:00:00' and '2021-09-30 23:59:59' group by client_id order by amount desc limit 0 ,5