题解 | #话题的分布情况#
话题的分布情况
https://www.nowcoder.com/practice/3f0d5c83b48b450888921b6189be288f
substring_index分割字符串并取出需要的部分
select substring_index(subject_set,',',1) subject_id1
,count(*) cnt
from comment_detail
where substring_index(substring_index(subject_set,',',2),',',-1) = '1002'
group by 1

