selecting-multiple-columns-fields-in-mysql-subquery and used in outer

FROM (SELECT col as name1, col2 as name 2 FROM ...) B

delete from exm_examresultdetail where ExamResultId not in (select bb.ee from (SELECT MAX(TotalObtainMarks) as aa,ExamResultId as ee FROM `exm_examresult` group by UserId,ExamId) bb)

http://stackoverflow.com/questions/5686271/selecting-multiple-columns-fields-in-mysql-subquery