Question

User     Product     count    Percentage 
User1    Product1     21        38.1818
User1    Product2     34        61.8182

上面提到的“百分比”是按count / total_count * 100计算的。我有以下代码实现这一点。

select user, product, count(id) as count, count(id)/55*100 from table1 where  
user=user1 group by product.

但是数字55已被硬编码。我不希望它被硬编码。因此，我怎样才能实现这一目标。我尽我所知尽力，但确实有效。

Answer 1

在MySQL中，您将使用join /相关子查询：

select user, product, count(id) as count,
       count(id) / (select count(*) from table1 tt1 where tt1.user = t1.user)
from table1 t1
where t1.user = user1
group by user, product;

在MySQL 8.0+中，您只需使用窗口函数：

select user, product, count(id) as count,
       count(id) / sum(count(*)) over (partition by user)
from table1 t1
where t1.user = user1
group by user, product;

有群组功能的问题

1 个答案: