Sql count查询始终返回1

Question

I'm using this query to find out the percentage of female employees. But somehow, when I combine that operation in one query like the one below, it always returns 1.0.

However, if I query separately and divide it, it's proper. I think I'm messing up with some syntax here.

What am I doing wrong?

employees and citizens are two tables.

SELECT (count(e.name)/count(c.name))
from citizens as c, employees as e
where c.gender=false and e.gender=false

Answer 1

You're simply creating a cross product between the rows in the two tables, and then counting the number of rows in the resulting cross product. You need to use separate queries to calculate each count:

SELECT (SELECT COUNT(*) FROM employees WHERE gender = false)/
       (SELECT COUNT(*) FROM citizens WHERE gender = false)

Answer 2

You're getting 1 because count returns integers.You need to cast them to floats so that you can get percentage. Also, only casting the numerator is enough in this case.This will return quotient in floats.

SELECT cast(count(e.name)as float)/count(c.name)
from citizens as c, employees as e
where c.gender=false and e.gender=false;