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select ks.login_name,ks.exam_name,ks.start_time,ks.end_time,cj.score
from (
     select u.user_id,u.login_name,e.* from  cphrms.EXAM_USER eu, cphrms.users u, cphrms.exam_info e
     where eu.user_id = u.user_id and eu.exam_id = e.exam_id
) ks
left join  
(select t.exam_id, t.user_id, sum(t.score) as score  from cphrms.user_answer t group by t.exam_id, t.user_id) cj
on
   ks.user_id = cj.user_id and ks.exam_id=cj.exam_id 
where ks.login_name = '19901' 
order by start_time