题解 | 话题的分布情况
话题的分布情况
https://www.nowcoder.com/practice/3f0d5c83b48b450888921b6189be288f
select subject_id1,
count(subject_id2) cnt
from(
select
substring_index(subject_set,',',1) subject_id1,
substring_index(substring_index(subject_set,',',2),',',-1) subject_id2
from comment_detail
)a
where subject_id2='1002'
group by subject_id1
