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Assignment1 solution
- 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)
- 8. Problem 2.1.b. wrong answer! Set different operation 할 때에 attribute 의 수가 동일해야 함 ! person_name company_name salary person_name
- 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
- 32. Problem 2.9.a. t1 t2 company_name count-distinct(person_name) max(count-tistinct(person_name)
- 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
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