Between these queries (Query 1 - 6), which would produce the same results having

Question

Between these queries (Query 1 - 6), which would produce the same results having these applied on our class running example, the University relational database with the small size tables? select distinct course_id from section where semester = Fall" and year = 2009 and course_id in (select course_id from section where semester = 'Spring' and year 2010); select course_id from section where semester = 'Fall' and year = 2009 intersect select course_id from section where semester = 'Spring' and year = 2010; select course_id from section where semester = "Fall" and year = "2009" and semester = "Spring" and year 2010"; select T.course_id from section as T, section as S where T, semester = "Fall" and T.year = "2009" and S.semester = "Spring" and S.year = "2010" and T.course_id = S.course_id; select course id from section as S where semester = 'Fall' and year = 2009 and exists (select * from section as T where semester = 'Spring' and year = 2010 and S.course_id T.course_id select course_id from section as T in section as S using (course_id) where T.semester = "Fall" and T. year = "2009 and S.semester = "Spring" and S.year = "2010;

Explanation / Answer

The queries 2, 4, 5 and 6 will producing same result, because all these queires are producing the course ids of the same subjects which were taught in in semester "Fall" in year "2009" as well as semster "spring" in year "2010".

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