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
题意分析：
每个订单号（order_num）各有多少行数（order_lines），并按 order_lines对结果进行升序排序
- 每个订单号：使用
group by分组 - 各有多少行数：
count()函数进行统计
select
order_num,
count(order_num) as order_lines
from
OrderItems
group by
order_num
order by
order_lines
#MySQL#
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