Question

我很难获得正确的查询：有两个表：articles和orders

我想从所有文章中获取一个列表，但按照订购时间排序。（不仅订购商品的次数，还包括金额）

orders：id, article_id, amount

articles：id, description

示例：

articles

1, apple
2, orange
3, lime

orders

1, 1, 5
2, 3, 1
3, 3, 2
4, 2, 1

输出应为：

1, apple,  5
3, lime,   3
2, orange, 1

Answer 1

这是一个基本的join和group by查询，是SQL语言的两个基础。如果要有效地使用数据库，应该学习该语言。

select a.`key`, count(o.id) as cnt, sum(amount)
from articles a left join
     orders o 
     on o.article_key = a.`key`
group by a.`key`
order by cnt desc;

Answer 2

select a.key, a.description, sum(amount) as sum_amount
from articles a
left join orders o on o.article_key = a.key
group by a.key, a.description
order by sum_amount desc

基于SUM对MySQL查询进行排序

2 个答案: