题解 | #截取出年龄#

select substring_index(substring_index(profile,',',3),',',-1) as age,count(*) as number from user_submit
group by age

substring_index(FIELD, sep, n)可以将字段FIELD按照sep分隔： (1).当n大于0时取第n个分隔符(n从1开始)之前的全部内容； (2).当n小于0时取倒数第n个分隔符(n从-1开始)之后的全部内容；

SELECT SUBSTRING_INDEX(SUBSTRING_INDEX(profile, ',', -2), ',', 1) AS age, count(*) AS number FROM user_submit GROUP BY age;

这一题我自己写错了是 count(*) AS number 里面写的是age 不是*