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1 p.1 of 10 INFS 4240/6240 (Section A) Database Management System Fall 2018 Test 3 December 4, :00 3:15 pm Q Q Q Name: Answers Q Q Q Total Answer all questions. Answer in the space provided. Please give a good effort to make your writing and your diagrams readable. Open Book, Open Notes. Use of cell phone is not allowed. Consultation with other people is not allowed.

2 p.2 of 10 Q.1-1 The Entity-Relationship Diagram below depicts the conceptual schema for an information system to keep track of project assignments in a certain company. The company is divided into Departments, each managed by a manager. Study the diagram, and determine if the statements from (a) to (j) are true or false according to the ER Model. Enter T (True) or F (False) in the corresponding space. (10 points, 1 point each) Staff ID works on Project ID Employee Project leads belongs to Manager manages Department Title DeptName (a) [ F ] An Employee must work on at least one Project. (b) [ T ] Every Project must have an Employee leading the Project. (c) [ F ] A Project may belong to two different Departments which jointly sponsor the Project. (d) [ F ] A Manager who leads a Project must also work on the same Project. (e) [ T ] Two Projects belonging to the same Departments must have different Project ID s.

3 p.3 of 10 (f) [ T ] Two different Managers must manage two different Departments. (g) [ T ] Two different Managers may have the same Title. (h) [ T ] An Employee may work on two different Projects led by two different Managers. (i) [ F ] If many Employees work on the same Project, only one of them can be a Manager. (j) [ T ] A Department may have no Projects belonging to the Department. Q.1-2 Based on the same Entity-Relationship Diagram from Q.1-1 above, for the multiple choice questions (k) to (n) below, choose one correct answer out of the choices of A, B, C or D. (8 points, 2 points each) (k) [ C ] There are 100 Employees in the company and 4 of them are Managers. How many Departments are there? [A] 1 or more. [B] at most 4. [C] exactly 4. [D] 4 or more. (l) [ D ] There are 100 Employees in the company and 4 of them are leading Projects. How many Projects are there? [A] 1 or more. [B] at most 4. [C] exactly 4. [D] 4 or more. (m) [ A ] There are 100 Employees and 4 different Projects in the company. How many Departments are there? [A] 1 or more. [B] at most 4. [C] exactly 4. [D] 4 or more. (n) [ B ] There are 100 Employees and 4 different Departments in the company. How many employees are leading Projects? [A] 1 or more. [B] at most 4. [C] exactly 4. [D] 4 or more.

4 p.4 of 10 Q.2 We have designed and developed a simple personnel database system to keep track of employee salary history in a company. The following ER Diagram illustrates our design. Study the diagram and answer the questions. [12 points] EmpID Effective Date Employee 1 received M Salary Record Name Department New Salary In our design, EmpID the employee ID identifies the employee, but we also keep the attribute information about the employee s name (Name), as well as the department the employee works for (Department). Every time an employee gets a pay raise, or adjustment, a Salary Record is filed to indicate the new salary level (NewSalary) and effective date (EffectiveDate) for the new salary. A new employee gets the first Salary Record to indicate the initial salary, effective on his/her start date. To implement the database design, we need to have two tables: Employee and SalaryRecord. The following is the SQL statement to create the Employee table. Notice that column Name is a Secondary Key of the table. CREATE TABLE Employee ( EmpID number Primary Key, Name text not null, Department text, Unique (Name) ); Q.2(a) Write the SQL statement to create the SalaryRecord table below. Use the following data types as appropriate: number for numerical data, date for date and currency for dollar amount such as salary. [4 points] CREATE TABLE SalaryRecord (EmpID number, EffectiveDate date, NewSalary currency, Primary Key (EmpID, EffectiveDate), Foreign Key (EmpID) references Employee (EmpID) );

5 p.5 of 10 Q.2(b) Since the Salary Change Records keep track of salary changes for every employee, we should be able to find the current salary of any employee by looking up the employee s latest salary change record. Use SQL to find the current salary of the employee named Tom Paine. (Hint: the salary change records applying to Tom Paine has the salary history; the current salary is the new salary on the latest salary change record. Use of SQL sub-query may make it easier.) [6 points] CREATE VIEW History(effDate, salary) as SELECT sr.effectivedate, sr.newsalary FROM SalaryRecord sr JOIN Employee e on SR.EmpID=e.EmpID WHERE e.name = Tom Paine ; SELECT salary as current salary FROM History WHERE effdate = (SELECT max(effdate) FROM History); Q.2(c) We recently decided to hire a new employee but he has the exact same name Tom Paine. He has a new employee id (EmpID). But when we tried to put the new employee information into our Employee table, the database system rejected the new entry because of Secondary Key violation. Write an SQL statement using the ALTER TABLE command to drop the Secondary Key constraint on the Employee table. [2 points] ALTER TABLE Employee DROP CONSTRAINT UNIQUE (Name);

6 p.6 of 10 Q.3 A nursing home for elderly people has commissioned us to design an information system for their library. The residents of the nursing use the library as members. If a member has read a book, he or she may also give the book a rating, so that others may use as a reference to learn whether or not the book is worth reading. In the friendly setting of the nursing home, the library keeps only the date, and what book is checked out by which member. There is no due date. When the book is returned, the information is erased so that the library keeps no information of circulation history, except to update the physical condition of the book for maintenance purpose. To provide for the residents at the nursing home, some of the book kept in the library has multiple copies, and some of these copies are in large print (for elderly members with difficulties in reading); some copies are in regular print. We need to design the database for the library information system. Here are the specific requirements: The residents of the nursing home are members of the library, and each member uses a unique nickname to identify himself/herself in the library. There is no need to keep any other information about each member except the nickname. Each published book of the library is uniquely identified by the ISBN. We also need to keep the information about the title and the author for each published book. If a member has read a book, the member may rate the book about its worthiness for reading. The rating is expressed in four different grades: A for excellent, B for good, C for fair, and D for poor. Each physical copy of a published book is further identified by a CopyNum (that is, a Copy Number). The CopyNum runs iteratively through the copies of each published book, as 1,2,, and so on, up to any number of copies. For each copy, we must also indicate the print size and its physical condition. The print size is Large print or Regular Print; the physical condition is expressed as 1,2,3, or 4. (1: new, 2: in use, 3: wearing out; 4 worn out) When a book copy is checked out, a note is made to keep the information who has checked out what book copy, along with the date. When the book copy is returned, the note is then erased, the book copy is examined to see if the physical condition should be updated when the book copy becomes available for other library members. The next page shows the Entity-Relationship Diagram depicting a conceptual schema we have designed for the database. However, the diagram is incomplete. We will continue to develop our design, as we go on to answer the questions respectively: first understand more about the relationships (the cardinality ratios); then we will add in the attributes; finally derive the relational schema that is, the collection of tables and how they may be related.

7 p.7 of 10 Q.3-1 has read Published Book (1,*) Member Should be (0,1) is printed on has checked out Book Copy For each of the following, check the correct answer: (6 points: 2 points each) The Relationship has read between Member and Published Book is: [ ] One-to-One [ ] One-to-Many from Member to Published Book [ ] Many-to-One from Member to Published Book [ ] Many-to-Many The Relationship is printed on between Published Book and Book Copy is: [ ] One-to-One [ ] One-to-Many from Published Book to Book Copy [ ] Many-to-One from Published Book to Book Copy [ ] Many-to-Many Regarding the participation in the Relationship is printed on : [ ] Both Published Book and Book Copy participate totally. [ ] Published Book participates totally and Book Copy partially. [ ] Published Book participates partially and Book Copy totally. [ ] Both Published Book and Book Copy participate partially.

8 p.8 of 10 Q.3-2 The same ER Diagram is illustrated below. Properly add the following attributes to the ER Diagram. These are the attributes of the entities or the relationships. Add them to the diagram below. (32 points) nickname rating: {A,B,C,D} (worthiness for reading) ISBN title author CopyNum (copy number) print size: {Large,Normal} condition: {1,2,3,4} (physical condition) date (check-out date) NOTE: If the attribute is a Key attribute, it should be underlined; if it is a Partial Key attribute for a weak entity set, it should be underlined by a dash line. There is no such thing as a Foreign Key in the ER Model. If an attribute is optional, also indicate that properly when adding the attribute to the diagram. rating: {A,B,C,D} ISBN title nickname has read Published Book (1,*) author Member Should be (0,1) has checked out is printed on Book Copy CopyNum date condition: {1,2,3,4} print size: {Large, Normal}

9 p.9 of 10 Q.3-3 For the ER Model completed with attributes from Q.3-2, translate the model into relational schema for the tables in a relational database. For each table, identify the columns, and indicate the columns which constitute the primary key (underline the column name label in the column heading), and if there are foreign keys, indicate the columns of each foreign key at the table where the foreign key is (i.e., the referring table) and name the referenced table the foreign key refers to, listing also the column name(s) of the referenced table corresponding to this foreign key. Do not just use arrows to point to the referenced table. (32 points) (NOTE: The weak entity set in the ER Diagram may have partial key attributes, but there is no such thing as a partial key in a relational table.) MEMBER nickname Published Book ISBN title author Book Copy ISBN CopyNum print size condition nickname date (null allowed) (null allowed) Foreign Key: (ISBN) refers to Published Book. Foreign Key: (Nickname) refers to MEMBER. has read nickname ISBN rating (null allowed) Foreign Key: (Nickname) refers to MEMBER. Foreign Key: (ISBN) refers to Published Book.

10 p.10 of 10 (In case you used the ER Diagram with mistake.) rating: {A,B,C,D} ISBN title nickname has read Published Book (1,*) author Member Should be (0,1) has checked out is printed on Book Copy CopyNum date condition: {1,2,3,4} MEMBER nickname print size: {Large, Normal} Published Book ISBN title author Book Copy ISBN CopyNum print size condition Foreign Key: (ISBN) refers to Published Book. has read Nickname ISBN rating (null allowed) Foreign Key: (Nickname) refers to MEMBER. Foreign Key: (ISBN) refers to Published Book. has checked out Nickname ISBN CopyNum date Foreign Key: (Nickname) refers to MEMBER. Foreign Key: (ISBN, CopyNum) refers to Book Copy

Name: Sample Answers Q.2(c) 7 7

Name: Sample Answers Q.2(c) 7 7 p.1 of 11 INFS 4240 (Section B) Database Management Systems Fall 2017 Practice for Test 2 (not for credit, but to help you prepare) Time allowed: 1 hour 15 minutes Q.1(a) 12 12 Q.1(b) 10 10 Q.1(c) 10 10