题解 | #截取出年龄#
截取出年龄
https://www.nowcoder.com/practice/b8d8a87fe1fc415c96f355dc62bdd12f
select age,count(a.device_id)number
from (select substring(profile,12,2) age, device_id from user_submit)a
from (select substring(profile,12,2) age, device_id from user_submit)a
group by age
考虑到sql的运行顺序，先from，子查询先出来age关键词，后续才能运行
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