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Date: Tue, 09 Mar 2004 02:41:52 -0300
From: Daniel Henrique Alves Lima <email_daniel_h@yahoo.com.br>
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To: pgsql-sql@postgresql.org
Subject: Help to simplify sample query
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    Hi guys, i have a new question about how to simplify a query. I have 
the tables area_course(cd_area,cd_course) and 
teacher_course(cd_teacher,cd_course) and a set of pairs of values 
{(1,2),(98,45),(11,0),...}.

    Now, i must to select the areas which courses appears in 
teacher_course and match with the set of pairs. Something like :

select cd_area from area a1 where
   exists (select * from teacher_course c2 where c2.cd_course = 
a1.cd_course and c2.cd_teacher = 1 and c2.cd_course = 2) and
   exists (select * from teacher_course c2 where c2.cd_course = 
a1.cd_course and c2.cd_teacher = 98 and c2.cd_course = 45) and
   exists (select * from teacher_course c2 where c2.cd_course = 
a1.cd_course and c2.cd_teacher = 11 and c2.cd_course = 0) and
....

    This is just a sample. The whole query is giant and its use other 
tables/columns. Is there a best way to write this query ?

    I don't think this is possible, but: Is there a efficient way to 
compare if the result of a query is a superset of the result of another ?




    I would appreciate any ideas/suggestions. Thanks !!!