题解 | #返回每个订单号各有多少行数#
返回每个订单号各有多少行数
https://www.nowcoder.com/practice/cf1f8d4a514d455aa0468718fb411f41
select distinct order_num,count(order_num) as order_lines from OrderItems group by order_num order by order_lines asc
严重出错，第一次写掉了group by 读题 每个订单号各有多少行，对订单号进行分组
