PostgreSQL四舍五入数值

Question

我正在尝试从以下查询中获得3个小数位的输出。

我得到的输出是2.2600

如果我在下面的舍入函数中将参数4更改为3，则输出将为2.300

这是不正确的，应该是2.26

Select date(time), 

    round((count(case WHEN status='404 NOT FOUND' THEN 1 END))
    /
    (count(*))::numeric,4) * 100 as error_percentage

from log GROUP BY date(time)
ORDER BY error_percentage DESC

Answer 1

您可以使用：

SELECT date(time), 
    ROUND(100.0 * (count(*) FILTER(WHERE status='404 NOT FOUND'))/(count(*)),3) 
    as error_percentage
FROM log 
GROUP BY date(time)
ORDER BY error_percentage DESC