with t as (
    select 
tag,
count(1) as cnt

from 
exam_record join 
examination_info on exam_record.exam_id=examination_info.exam_id

group by tag 
)



select 
t.tag,t1.cnt as answer_cnt
from t join t as t1  on upper(t.tag)=t1.tag and t.tag<>t1.tag and t.cnt<3