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Unformatted text preview: WHERE l.cid=c.cid AND (l.year=2000 OR l.year=1999); Answer: Find the names of courses that are taught in 2001 but not taught in 2000 or 1999. π name ( σ year = 2001 (lecturing ⋈ courses)) - π name ( σ (year = 1999 ∨ year = 2000) (lecturing ⋈ course)) (3). SELECT c.name FROM lecturing l1, lecturing l2, courses c WHERE l1.cid=l2.cid AND l1.cid=c.cid AND l1.sid=l2.sid AND l1.year=1999 AND l2.year=2000; Answer: Find the names of the courses that are taught by the same staff in both 1999 and 2000 π name ( σ year = 1999 ∧ year2 = 2000 (lecturing ⋈ courses ⋈ ρ year -> year2 lecturing) (4). SELECT s.lastname FROM staff s WHERE s.sid NOT IN (SELECT l.sid FROM lecturing l); Answer: Find the last names of the staff that do not teach π lastname (( π sid staff - π sid lecturing) ⋈ staff)...
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- Fall '08
- 1920, Microsoft SQL Server, Personal name, Family name