2010-1 Database. assignment #1 (relation algebra) Taemin Lee. Dataknow Lab. Computer Science Education Dept. Korea University.

1. Database System Conceps : CH2 Exercises and solutions

3. Problem 2.1.

4. Problem 2.1.a. σ (Street = M_street ∧ City = M_city) ( 위 relation) t1 ← employee manages t2 ← ρ manager (manager_name, m_street, m_city) (employee) Person_name Street City Manager_name M_street M_city Person_name Street City Manager_name Manager_name M_street M_city

5. Problem 2.1.a. t1 ← employee manages t2 ← ρ manager (manager_name, m_street, m_city) (employee) Π (person_name) σ (Street = M_street ∧ City = M_city) (t1 t2) Person_name Street City Manager_name M_street M_city Person_name Street City Manager_name Manager_name M_street M_city

6. Problem 2.1.a. t1 ← employee manages t2 ← ρ manager (manager_name, m_street, m_city) (employee) Π (person_name) σ (Street = M_street ∧ City = M_city) (t1 t2)

7. Problem 2.1.b.

8. Problem 2.1.b. wrong answer! Set different operation 할 때에 attribute 의 수가 동일해야 함 ! person_name company_name salary person_name

9. Problem 2.1.c.

10. Problem 2.1.c.

11. Problem 2.1.c.

12. Problem 2.3.a.

13. Problem 2.3.a. wrong answer! Update 할 때에 정보의 누수를 조심 !

14. Problem 2.3.b.

15. Problem 2.5.a.

16. Problem 2.5.b. & 2.5.c

17. Problem 2.5.d. & 2.5.e

18. Problem 2.6.

19. Problem 2.6.a.

20. Problem 2.6.a.

21. Problem 2.6.b. & 2.6.c

22. Problem 2.7.a.

23. Problem 2.7.b.

24. Problem 2.7.b.

25. Problem 2.7.c.

26. Problem 2.8.a. t1 account_number count(customer_name)

27. Problem 2.8.b. account customer 1 customer 2 customer 3

28. Problem 2.8.b. account customer 1 customer 2 customer 3 depositor 1 account 1 customer 1 depositor 2 account 2 customer 2 depositor 3 account 3 customer 3

29. Problem 2.8.b. account customer 1 customer 2 customer 3 customer 1 customer 2 customer 3 account 1 account 2 account 3 depositor 1 account 1 customer 1 depositor 2 account 2 customer 2 depositor 3 account 3 customer 3

30. Problem 2.8.b. account customer 1 customer 2 customer 3 customer 1 customer 2 customer 3 account depositor 1 account 1 customer 1 depositor 2 account 2 customer 2 depositor 3 account 3 customer 3

31. Problem 2.8.b.

32. Problem 2.9.a. t1 t2 company_name count-distinct(person_name) max(count-tistinct(person_name)

33. Problem 2.9.b.

34. Problem 2.9.b.

35. Problem 2.9.c.

36. Problem 2.11.a

37. Problem 2.11.b.

38. Problem 2.11.c. common mistake! t1 name 이 존재하지 않음 ! empno count_distinct(isbn) empno name office age isbn title authors publisher date

39. Problem 2.11.c. & 2.11.d

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