Question

我有以下代码：

select c.category
,sum(b.is_open) as open
,count(b.name) as total
from business b inner join category c on b.id=c.business_id
group by c.category
order by sum(b.is_open) desc
limit 10

这给了我以下数据集：

+------------------+------+-------+
| category         | open | total |
+------------------+------+-------+
| Restaurants      |   53 |    71 |
| Shopping         |   25 |    30 |
| Food             |   20 |    23 |
| Health & Medical |   16 |    17 |
| Home Services    |   15 |    16 |
| Beauty & Spas    |   12 |    13 |
| Nightlife        |   12 |    20 |
| Bars             |   11 |    17 |
| Active Life      |   10 |    10 |
| Local Services   |   10 |    12 |
+------------------+------+-------+

但是，如果我将第2行和第3行更改为：

sum(b.is_open) / count(b.name) as '%'

我一直没有得到一个特定的值，而是一直为零。我试图将两列都转换为十进制类型（尽管看起来它们一开始就是这样），但没有用。为什么我无法获得正确的结果？我正在用SQLite编写查询。

Answer 1

尝试使用浮点算术代替整数算术：

1.0 * sum(b.is_open) / count(b.name) as '%'

SQL-将一列除以另一列

1 个答案: