我有一张如下表:
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)列中找到比例。
我需要一个查询来执行此操作。
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:
| MALE_RATIO | FEMALE_RATIO |
|------------|--------------|
| 0.5 | 0.5 |
尝试这样的事情
select sum(case when gender = 'MALE' then 1 else 0 end) / count(*) * 100 as perc_male,
sum(case when gender = 'FEMALE' then 1 else 0 end) / count(*) * 100 as perc_female
from students
这应该给你实际的比率,并且应该在 MySQL 和 SQL Server 中很少或没有修改的情况下工作。您可能需要稍微修改一下强制转换语句 - 我的 MySQL 生锈了,我认为它的处理方式可能略有不同。
SELECT
(CAST((SELECT COUNT(*) FROM tblName WHERE Gender='MALE') AS FLOAT) /
CAST((SELECT COUNT(*) FROM tblName WHERE Gender='FEMALE') AS FLOAT))
AS ratioMaleFemale;
你已经很接近了:
select (select count(*)
from table where gender='MALE' )/count(*)*100 as percentage_male,
(select count(*)
from table where gender='FEMALE' )/count(*)*100 as percentage_female
from table;
创建表Employee( EmpID int NOT NULL, EmpName Varchar (50), 性别查尔 (50), 工资整数, 城市魅力(50) ) 插入员工值 (1, 'Arjun', 'M', 75000, 'Pune'), (2, 'Ekadanta', 'M', 125000, '班加罗尔'), (3, '拉丽塔', 'F', 150000, '马图拉'), (4, '马达夫', 'M', 250000, '德里'), (5, '维萨卡', 'F', 120000, '马图拉')
从员工中选择*
选择 COUNT(性别)作为 [Total Emp], (从员工中选择 COUNT(性别) 其中性别 = 'M') 100/计数 () 作为[男性比例], (从员工中选择 COUNT(性别) 其中性别 = 'F') 100/计数 () 作为 [女性比例] 来自员工
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