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select a.S# from (select s#,score from SC where C#='001') a,(select s#,score
from SC where C#='002') b
where a.score>b.score and a.s#=b.s#;

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SQL code:
select a.s#
from sc a join sc b on a.s#=b.s#
where a.c#='001' and b.c#='002' and a.score>b.score



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