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Database System Review

Database System Review. Nội dung thi. Thời gian thi : 90 phút Hình thức thi : lý thuyết ( trắc nghiệm + trả lời ngắn ) + bài tập ( đề mở ) Cấu trúc bài thi : A. Lý thuyết tổng hợp : 2.5đ B. Bài tập : 7.5đ Thiết kế E(E)RD : 3đ

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Database System Review

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  1. Database System Review

  2. Nội dung thi • Thờigianthi: 90 phút • Hìnhthứcthi: lýthuyết (trắcnghiệm + trảlờingắn) + bàitập (đềmở) • Cấutrúcbàithi: • A. Lýthuyếttổnghợp : 2.5đ • B. Bàitập : 7.5đ • Thiếtkế E(E)RD : 3đ • Ánhxạ : 1đ • Viết SQL : 1.5đ • Bảomật : 0.5đ • Chuẩnhóa, tìmkhóa : 1.5đ

  3. Sample questions 1. Given the below database schema

  4. Sample questions • (cont.) • Map this schema into ERD • Write SQL statements to: • For each book that is loaned out from the "Sharpstown" branch and whose DueDate is today, retrieve the book title, the borrower's name, and the borrower's address. • For each library branch, retrieve the branch name and the total number of books loaned out from that branch • Retrieve the names, addresses, and number of books checked out for all borrowers who have more than five books checked out

  5. Sample questions

  6. Sample questions • Given a relation Emp, the degree of the Emp relation is? • Given a relation SalGrade, the cardinality of the SalGrade relation is? • Given a relation Emp, a relation schema of the Emp relation is? • Given a relation Emp, is it possible to conclude that the Emp relation is in the first normal form?

  7. Sample questions • Given a relation Emp, which SQL statements are used in order to insert into the Emp relation the data about a new employee whose empno is 1234, enameis Tam, job is salesman, MGR is 7698, hire date is 15/07/1996, salary is 1800, and department is sales

  8. Sample questions • Insert into EMP values(1234, ' Tam', ' salesman ', 7698, TO_DATE(' 15/07/1996', 'DD-MM-YYYY'), 1800, NULL,30); • Insert into EMP values(1234, ' Tam', ' salesman ', 7698, TO_DATE(' 15/07/1996', 'DD-MM-YYYY'), 1800, NULL,(SELECT DEPNO FROM DEPT WHERE DNAME = ‘Sales”)); • Insert into EMP (Empno, Ename, Job, MGR, HireDate, SAL, DepNo) values(1234, ' Tam', ' salesman ', 7698, TO_DATE(' 15/07/1996', 'DD-MM-YYYY'), 1800, 30); • All a, b, and c are correct. • None of them is correct.

  9. Sample questions • Given a relation Emp, which SQL statements are used in order to insert into the Emp relation the data about a new employee whose empno is 2345, ename is Tam, job is Manager, MGR is Null, hire date is 15/07/1996, salary is 1800, and department is human resource

  10. Sample questions • Insert into EMP values(2345, ' Tam', ‘Manager ', NULL, TO_DATE(' 15/07/1996', 'DD-MM-YYYY'), 1800, NULL, NULL); • Insert into EMP values(1234, ' Tam', ' salesman ', NULL, TO_DATE(' 15/07/1996', 'DD-MM-YYYY'), 1800, NULL,(SELECT DEPNO FROM DEPT WHERE DNAME = ‘human resource”)); • All a, b are correct. • Both a and b are unable to be used for that insertion because there is no data about the deparment of human resource in the Dept relation and the foreign key constraint is therefore violated.

  11. Normalization

  12. Sample questions 3. Consider this database with the following functional depencies (primary key is (FactoryNumber, ProductNumber) and candidate key is (FactoryName, ProductNumber)) Production (FactoryNumber, FactoryName, ProductNumber, Status, Location, QtyOnDay) • FactoryNumberFactoryName • FactoryNumberStatus • StatusLocation • LocationStatus • FactoryNumber, ProductNumberQtyOnDay • FactoryName, ProductNumberQtyOnDay

  13. Sample questions • Given database with its relation Production as shown above, which normal form is the Production relation in? a. First normal form b. Second normal form c. Third normal form d. Boyce-Codd normal form • Can you normalize it into the highest level?

  14. More exercises Consider the relation R, which has attributes that hold schedules of courses and sections at a university. R = {CourseNo, SecNo, OfferingDept,CreditHours, CourseLevel, InstructorSSN,Semester, Year, Days_Hours, RoomNo,NoOfStudents} Suppose that the following functional dependencies hold on R:  {CourseNo} -> {OfferingDept, CreditHours,CourseLevel}  {CourseNo, SecNo, Semester, Year} ->{Days_Hours, RoomNo, NoOfStudents,InstructorSSN}  {RoomNo, Days_Hours, Semester, Year} -> {InstructorSSN, CourseNo, SecNo} • Try to determine which sets of attributes form keys of R. How would you normalize this relation?

  15. More exercises Consider the following relation for published books: BOOK (Book_title, Authorname, Book type Book_type, Listprice, Author_affil,Publisher) Author_affil referes to the affiliation of the author Suppose the following dependencies exist:  Book_title -> Publisher, Book_type  Book Book_type -> Listprice  Author_name -> Author-affil Find keys and normalize this relation into 3NF

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