sql - Ignite: SQL query to calculate probability of a column

Question

Gender
-------
Female
Male
Male
Male
Female
Female
Male
Female

Here i want to calculate probability of gender column and following query i tried, but it's not working.

SELECT (count(*)/(SELECT count(*) from DIABETIC_TOPIC) as probability from DIABETIC_TOPIC group by gender order by gender;

what i missed?

标签： sqlignite

Answer 1

我将在非分组查询中交叉加入分组查询，并将它们分开：

SELECT     gender, cnt_gender / cnt * 100 AS probability
FROM       (SELECT   gender, COUNT(*)
            FROM     diabetic_topic
            GROUP BY gender) a
CROSS JOIN (SELECT COUNT(*) AS cnt
            FROM   diabetic_topic) b