Help to simplify sample query
От | Daniel Henrique Alves Lima |
---|---|
Тема | Help to simplify sample query |
Дата | |
Msg-id | 404D5920.40104@yahoo.com.br обсуждение исходный текст |
Ответы |
Re: Help to simplify sample query
Re: Help to simplify sample query |
Список | pgsql-sql |
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 !!!
В списке pgsql-sql по дате отправления: