Sql 计算组内的百分比

给定一个表，其中包含以下命令：

select sex, count(*) from my_table group by sex;
select sex, employed, count(*) from my_table group by sex, employed;

给出：

  sex  | count 
-------+------
male   | 1960 
female | 1801

以及：

我在写一个查询时遇到了困难，这个查询将计算每个性别组的就业率。因此，输出应如下所示：

 sex     | employed | count  | percent
---------+----------+--------+-----------
 male    | f        |  1523  | 77.7% (1523/1960)
 male    | t        |   437  | 22.3% (437/1960)
 female  | f        |  1491  | 82.8% (1491/1801)
 female  | t        |   310  | 17.2% (310/1801)

---

您可以使用子选择和联接来执行此操作：

SELECT t1.sex, employed, count(*) AS `count`, count(*) / t2.total AS percent
  FROM my_table AS t1
  JOIN (
    SELECT sex, count(*) AS total 
      FROM my_table
      GROUP BY sex
  ) AS t2
  ON t1.sex = t2.sex
  GROUP BY t1.sex, employed;

---

我想不出其他的方法了。

可能太晚了，但对于即将到来的搜索者来说，可能的解决方案是：

select sex, employed, COUNT(*) / CAST( SUM(count(*)) over (partition by sex) as float)
  from my_table
 group by sex, employed

通过IO统计，这似乎是最有效的解决方案-可能取决于要查询的行数-在上面的数字上进行测试

同样的态度也可用于获得男性/女性百分比：

select sex, COUNT(*) / CAST( SUM(count(*)) over () as float)
  from my_table
 group by sex

问候,，

---

Jan

非常感谢，经过一些小修改后，您的解决方案成功了！可能重复的

select sex, COUNT(*) / CAST( SUM(count(*)) over () as float)
  from my_table
 group by sex