Question

在下表中，我需要找到处于州内的男性百分比＆＃39;。

  select count(*) from table where state = 'nyc' and gender = 'male';

给了我来自纽约的男性人数。我需要来自纽约市的男性比例为75％。

+-------+-------+--------+
| name  | state | gender |
+-------+-------+--------+
| Jon   | nyc   | male   |
+-------+-------+--------+
| obama | LA    | male   |
+-------+-------+--------+
| kat   | nyc   | male   |
+-------+-------+--------+
| andy  | nyc   | male   |
+-------+-------+--------+
| sri   | nyc   | female |
+-------+-------+--------+

期望的输出：

state，male_percentage - ＆gt;纽约，75％

3为男性，1为女性，总数为4，来自纽约。

Answer 1

select count(*)/(select count(*) from table where gender='male')*100
from table where state = 'nyc' and gender = 'male';

Answer 2

从表中选择一个

 select state ,100 * sum( IF(gender = 'male',1,0) ) / count(*) 
    from table where state = 'nyc' 
    group by state

Answer 3

您可以使用子查询执行此操作：

(select count(*) from table where gender='male' and state = 'nyc')/
(select count(*) from table where state = 'nyc') *100;

但它可以更容易，更明智的恕我直言，在PHP中做到这一点

Answer 4

select (select count(*) from table where state='nyc' and gender='male') * 100.0 / count(*)
from table

是最简单的方法。

适用于sqlite3

sql查询来计算百分比

4 个答案: