select 
ui.uid,er.exam_id,
round(avg(score),0) as avg_score

from user_info ui
join exam_record er on ui.uid = er.uid
join examination_info ei on ei.exam_id = er.exam_id

where (nick_name rlike '^牛客[0-9]+号$' or nick_name rlike'^[0-9]+$')
and submit_time is not null
and tag rlike '^c|C'
group by ui.uid,er.exam_id
order by ui.uid,avg_score

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