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 order_num, COUNT(*) order_lines FROM OrderItems GROUP BY order_num ORDER BY order_lines
题解:
1.查询行数,就是记录数
2.查询每个订单号的,也就是分组
3.按订单记录数升序排序
思路:
1.查询记录数,使用count计数函数
2.按订单号分组,使用group by
3.升序排序,使用order by