如何使用sql查询来计算比率? [英] How to calculate ratio using sql query?
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问题描述
我有一个如下表:
ID Name Department Gender
1 Crib MA MALE
2 Lucy Bsc FEMALE
3 Phil Bcom MALE
4 Ane MA FEMALE
我有1000行这样的记录.我想从所有学生的性别(男性和女性)栏中找到比率.
I have 1000 row of records like this. I want to find the ratio from column Gender( MALE & FEMALE) of all students.
我需要一个查询来执行此操作.
I need a query to perform this.
推荐答案
MySQL 5.5.32架构设置:
CREATE TABLE table1
(`ID` int, `Name` varchar(4), `Department` varchar(4), `Gender` varchar(6))
;
INSERT INTO table1
(`ID`, `Name`, `Department`, `Gender`)
VALUES
(1, 'Crib', 'MA', 'MALE'),
(2, 'Lucy', 'Bsc', 'FEMALE'),
(3, 'Phil', 'Bcom', 'MALE'),
(4, 'Ane', 'MA', 'FEMALE')
;
查询1 :
SELECT sum(case when `Gender` = 'MALE' then 1 else 0 end)/count(*) as male_ratio,
sum(case when `Gender` = 'FEMALE' then 1 else 0 end)/count(*) as female_ratio
FROM table1
结果 :
Results:
| MALE_RATIO | FEMALE_RATIO |
|------------|--------------|
| 0.5 | 0.5 |
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