利用Mysql实现将出生日期转换为年龄并统计人数

SELECT * FROM `student`

SELECT id, name, birthday, TIMESTAMPDIFF(YEAR,student.birthday,CURDATE()) as age FROM `student`

SELECT
	GROUP_CONCAT(a.id) as ids,
	GROUP_CONCAT(a.name) as names,
	CASE
		WHEN a.age<18 THEN '少年'
		WHEN a.age>=18 AND a.age< 40 THEN '青年'
		WHEN a.age>=40 AND a.age< 60 THEN '中年'
	END as age,
	count(a.id) as count
FROM
	(SELECT id, name, birthday, TIMESTAMPDIFF(YEAR,student.birthday,CURDATE()) as age FROM `student`) as a
GROUP BY
	CASE
		WHEN a.age<18 THEN '少年'
		WHEN a.age>=18 AND a.age< 40 THEN '青年'
		WHEN a.age>=40 AND a.age< 60 THEN '中年'
	END