mysql - 如何从具有多个条件的mysql数据库中随机抽取样本

Question

我有一张包含一些用户信息、性别、出生日期、“类别”等的表格

我需要随机抽样，但结果如下：

75% 女性
25% 男性

50% 25-35 岁
40% 36-40岁
10% 41-60 岁

共2000记录。

无论如何可以直接在 MySQL 中执行此操作吗？

Answer 1

对于每个 sql 查询，您不能在 Union 语句中使用 order by 或 limit。它们可以在最后使用。

所以最好使用存储过程来输出。

CREATE PROCEDURE USER_DATA_RAND()
BEGIN
CREATE TEMPORARY TABLE USER_TMP
ID INT,
DATE_OF_BIRTH DATE,
CATEGORY STRING,
AGE INT)
INSERT INTO USER_TMP
select sex, date_of_birth, `category`,age from users where age between 25 and 35 and sex = 'male' order by rand() limit 2000*0.5*0.25) ;
INSERT INTO USER_TMP
select sex, date_of_birth, `category`,age from users where age between 25 and 35 and sex = 'female' order by rand() limit 2000*0.5*0.75) ;
INSERT INTO USER_TMP
select sex, date_of_birth, `category`,age from users where age between 36 and 40 and sex = 'male' order by rand() limit 2000*0.40*0.25) ;
INSERT INTO USER_TMP
select sex, date_of_birth, `category`,age from users where age between 36 and 40 and sex = 'female' order by rand() limit 2000*0.40*0.75) ;
INSERT INTO USER_TMP
select sex, date_of_birth, `category`,age from users where age between 41 and 60 and sex = 'male' order by rand() limit 2000*0.10*0.25) ;
INSERT INTO USER_TMP
select sex, date_of_birth, `category`,age from users where age between 41 and 60 and sex = 'female' order by rand() limit 2000*0.10*0.75) ;

SELECT * FROM USER_TMP;
END