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
http://www.nowcoder.com/practice/cf1f8d4a514d455aa0468718fb411f41
方法:count()函数+group by分组的使用
select
order_num,
count(order_num) as order_lines
from
OrderItems
group by
order_num
order by
order_lines asc