mysql统计各年龄段的数量

1.表数据

2.统计各年龄段的人数。1-10，11-20，20+，我用的是CASE WHEN的方式实现的。

select age_temp,count(*) as total from (
select age,
case
when age between 1 and 10 then '1-10'
when age between 11 and 20 then '11-20'
when age >20 then '20+'
end as age_temp
from user
)t_user group by age_temp;

3.查询用户信息，并标明用户年龄处于哪个年龄段，1-10，11-20，20+。

select *,
case
when age between 1 and 10 then '1-10'
when age between 11 and 20 then '11-20'
when age >20 then '20+'
end as age_range
from user;