Select查询

Question

我想创建此SQL查询条件查询：

SELECT * FROM `Product` p 
ORDER BY (SELECT COUNT(*) FROM `Sale` WHERE `product_id` = p.id) DESC 

我不能找到一种方法，与子查询做...

Answer 1

Order By仅适用于一列是存在于select部分。

所以基本上像这样将工作：

SELECT Group, COUNT(*) as total 
FROM table 
GROUP BY Group 
ORDER BY total DESC 

因此，对于你的情况下，你可以这样做以下：

SELECT *, (SELECT COUNT(*) FROM `Sale` WHERE `product_id` = p.id) as total FROM `Product` p 
ORDER BY total DESC 

注：这是完全未经测试。

Answer 2

尝试的隐式连接：

select * 
from (
    select 
     p.*, 
     (select count(*) from sale s where s.product_id = p.id) as cnt 
    from product p 
)a 
order by cnt desc