27.返回每个订单号各有多少行数 OrderItems 表包

[单选题]

27.返回每个订单号各有多少行数

OrderItems 表包含每个订单的每个产品

order_num

a002

a004

a007

【问题】编写 SQL 语句，返回每个订单号（order_num）各有多少行数（order_lines），并按 order_lines对结果进行升序排序。

【示例结果】返回订单号order_num和对应订单号的行数order_lines

【示例解析】

订单号a002有3行订单记录也是最多的订单号故排在最后一位返回，相同订单行数的订单无需过多处理。

select order_num, count(*) as order_lines
from OrderItems
group by order_num
order by order_num asc

select count(order_num) order_lines
from OrderItems
group by order_num
order by order_lines

select count(order_num) as order_lines
from OrderItems
order by order_lines

select order_num,count(*) as order_lines
from OrderItems
group by order_num
order by order_lines

查看正确选项

牛客438200247号

因为已经按照订单编号分好组了，count(*)是组内计数

发表于 2022-05-03 12:50:05 回复(0)

提交观点

问题信息

来自：SQL必知必会（下）

上传者：小小

难度：

1条回答 83收藏 513浏览

扫一扫，把题目装进口袋