SQL统计哪种类型的书借出最多

Question

书籍的信息在Book5库里面，借阅的记录在Borrow1里面，将两个表连接之后又无法用以下的代码：
select CONVERT(varchar,cno,120),count() as 'number'from Borrow1
where borrow_date>'2021-2-17' group by Convert(varchar,cno,120)
order by count() desc
来进行计数，希望大家的指点。

Answer 1

这样？

select booktype,COUNT(1) borrownum from borrow1
left join book5 on book5.id=borrow1.bookid
group by booktype
order by borrownum desc