mysql中一张（居民）表按年龄段查询数据

知识点：

    用mysql,按年龄段查询一张居民的数据（各年龄段居民的个数）

1.如：查询resident(居民表)，按照各年龄段，统计人数

2.mysql语句如下：

select ageproportion as ‘年龄段‘,count(*) as ‘人数‘ from
(
     SELECT
     CASE
       when age>0 and age<=10 then ‘0-10岁‘
       when age>10 and age<=20 then ‘10-20岁‘
       when age>20 and age<=30 then ‘20-30岁‘
       when age>30 and age<=40 then ‘30-40岁‘
       when age>40 and age<=50 then ‘40-50岁‘
       when age>50 and age<=60 then ‘50-60岁‘
       else ‘60岁以上‘
      
     END
     as ageproportion from resident
)a GROUP BY ageproportion 

3.查询结果：