namib I A U n IVERS I TY

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1 namib I A U n IVERS I TY OF SCIEnCE AnD TECH n 0 LOGY FACULTY OF COMPUTING AND INFORMATICS DEPARTMENT OF COMPUTER SCIENCE QUALIFICATION: BACHELOR OF COMPUTER SCIENCE QUALIFICATION CODE: 07BACS LEVEL: 5 COURSE: Database Fundamentals DATE: July 2016 DURATION: 3 hours COURSE CODE : DBF510S SESSION: 2 MARKS: 100 SECOND OPPORTUNITY EXAMINATION QUESTION PAPER EXAMINER(S) MRS. JOSEPHINA MIKKA MODERATOR: MR. ISAAC NHAMU THIS QUESTION PAPER CONSISTS OF 11 PAGES {Excluding this front page) INSTRUCTIONS 1. Answer ALL the questions. 2. Questions 2 and 3 must be answered on the Question paper and the sheets attached to the answer sheet. 3. Write clearly and neatly. 4. Number the answers clearly. 5. When answering questions you should be guided by the allocation of marks in [ ]. Do not give too few or too many facts in your answers. PERMISSIBLE MATERIALS 1. Non programmable Scientific Calculator.

2 QUESTION 1: MULTIPLE CHOICES [30] 1. A Gender field can hold only the values M or F. This is an example of: A. key integrity B. domain integrity C. referential integrity D. logical integrity 2. The EmployeeiD field in an employee table cannot be left blank. This is an example of: A. key integrity B. domain integrity C. referential integrity D. schema integrity 3. The person responsible for the database technology, database design and construction consultation, security, backup and recovery, and performance tuning is known as a (n): A. data administrator B. database administrator C. system owner D end-user 4. Which language is used by the DBMS to physically establish those record types, fields, and structural relationships in a relational database? A. DML B. DOL C. DBA D. CASE 5. The physical, relational database implementation of a data model is known as a: A. scenario B. role model C. schema D. primary data model 6. Which of the following is NOT a high-performance relational DBMS? A. Oracle B. IBM DB2 C. Microsoft SQL Server D. Microsoft Access 7. Files that contain relatively static data that can be shared by applications to maintain consistency and improve performance are known as: A. document B. table look-up c. archival D. audit 1

3 8. A database that stores data extracted from operational databases for the purpose of data mining is called a (n): A. transactional database B. personal database C. workgroup database D. data warehouse 9. Which of the following is an acceptable technique for implementing supertype/subtype entities? A. Each supertype and subtype can be implemented with a separate table. B. The subtypes may be collapsed into the supertype to create a single table. C. The supertype's attributes could be duplicated in a table for each subtype. D. all of these 10. The underlying design of a table is referred to as the: A. source file B. structure c. caption D. archival 11. Pointers to the records of a different file in a database, they are used to link records of one type to those of another type: A. attributes B. referential pointers C. descriptive fields D. foreign keys 12. Which is not true about surrogate keys? A. They are short. B. They are fixed. C. They have meaning to the user. D. They are numeric. 13. A staff member called Maria realizes that her name is misspelt to Mary in a database. Choose the correct answer that updates firstname, Mary to firstname, Maria in the table called staff. A. UPDATE RECORD staff SET FName = 'Maria' WHERE FName = 'Mary'; B. UPDATE staff SET FName ='Maria' WHERE FName ='Mary'; C. UPDATE staff SET INTO FName = 'Maria' WHERE FName = 'Mary'; D. UPDATE RECORD staff SET INTO FName ='Maria' WHERE FName ='Mary'; 2

4 14. A goal of normalization is to minimize A. the number of relationships B. the number of entities C. the number of tables D. dataredundancy 15. A table that satisfies 2NF A. always satisfies 1NF B. may violate 1NF C. always satisfies 3N F D. always satisfies BCNF 16. On an entity-relationship diagram, a diamond shape represents a A. multivalued attribute B. data flow C. entity D. relationship 17. Based on Figure 1 the BOOKS and MEMBER entities are related to each other. The relationship on the MEMBER side indicates that: BOOKS MEMBER PK ISBN PK MEMBERID * TITLE ~ o PRICE O,N borrow (O,l) :> { borrowed by *NAME * ADDRESS o PHONE o Figure 1 A. A BOOKS may be borrowed by one or more MEMBER. B. A MEMBER may borrow one BOOK. C. A BOOKS may be borrowed by zero or one MEMBER only. D. A MEMBER may borrow zero or more BOOKS. 3

5 18. is the ability of the DBMS to recover the committed transaction updates against any kind of system failure. A. Consistent B. Isolated C. Durable D. Atomic 19. Deadlocks are possible only when one of the transactions wants to obtain a{n) lock on a data item. A. Binary B. Exclusive C. Shared D. Complete 20. refers to the requirement that other operations cannot access data that has been modified during a transaction that has not yet been completed. A. Consistent B. Isolated C. Durable D. Atomic 21. Which of the following term below refers to the statement stated below? All of the tasks of a database transaction must be completed If incomplete due to any possible reasons, the database transaction must be aborted. A. Consistent B. Durable C. Atomic D. Isolated 4

6 22. Choose the correct Entity Relationship Model diagram based on the situation given. 11 Each INSTRUCTOR may teach one or more CLASS" 11 Each CLASS is taught by one INSTRUCTOR" A. INSTRUCTOR 1 1 CLASS (0, N) (1,1) B. INSTRUCTOR 1 1 teac CLASS (0,1) (1,1) c. INSTRUCTOR 1 M CLASS (1,N) (1,1) D. 1 M INSTRUCTOR L..., (O,N) (1,1) CLASS 5

7 23. produces the relation that has attributes of Rl and R2 A. Cartesian product B. Difference C. Intersection D. Product 24. Which are the two ways in which entities can participate in a relationship? A. Passive and active B. Total and partial C. Simple and Complex D. All ofthe above 25. Which of the following database activities allow for the actual retrieval and use of a database? A. Enterprise modeling B. Logical database design C. Physical database design and definition D. Database implementation 26. Whose role is it to determine the requirements and design for a database? A. Database analysts B. Database administrators C. Both A and B. D. Neither A or B. 27. Which of the following is a comparison operator in SQL? A. = B. LIKE C. BETWEEN D. All of the above 28. What do you need if you should enforce many-to-many relationship between two tables? A. Parent table B. Child table C. Junction table D. Many-to-many relationship can't be created in database 6

8 29. An entity set that does not have sufficient attributes to form a primary key is a A. strong entity set B. weak entity set C. simple entity set D. primary entity set 30. In a craw's foot cardinality notation a circle indicates A. one B. many C. zero D. one and only one 7

9 QUESTION 2: TRUE\FALSE (10] Each statement below is either TRUE or FALSE. Choose the most appropriate one Questions T F 2.1 Placing Null values for an attribute is avoided as they do not have any specific meaning. 2.2 GROUP BY is an example of aggregate function. 2.3 Modifying the database without ensuring that transaction will commit may leave database in a consistent state. 2.4 Table in second normal forms {2NF) eliminates all hidden dependencies 2.5 A database is ordered collection of data. 2.6 Update anomalies can occur in a normalized relation. 2.7 SQL DROP is used to remove objects from the database. 2.8 A good data model is complex. As a general rule, the data attributes that describe an entity should describe all possible characteristics of that entity. 2.9 Most database management systems store both user data and metadata During the creation of database schemas, NULL means the field must have a value;. whereas, NOT NULL means the field must not have a value. 8

10 QUESTION 3: Match the descriptions/definitions in column X of Table 3.1 with the word/phrases in column V in Table 3.2, Use the corresponding letters A, B, C,... N from Table 3.2 to match the descriptions/definitions in Table 3.1. Fill in your answer in the column marked Match in Table 3.1. Attach this page to your answer sheet. [10] X Match 3.1 High level data model 3.2 Joint operation on two tables is a sunset of 3.3 Attribute of an entity having more than one value 3.4 To suppress any duplicate values in any column this clause is used 3.5 A relational database in 3NF and many still have undesirable data-redundancy because 3.6 Elimination of transitive dependency on key attribute 3.7 When an entity is related to itself 3.8 X-7Y if X determines Y uniquely 3.9 Relationship of a weak entity with it's owner entity 3.10 Command used to modify record of the table v Table 3.1 A B Multivalued Modify c Non-trival FD,s involving prime attribute on RHS D E F G H I J K L M Third normal form Update Conceptual level Cross-Product Distinct ER Model Recursive relationship Composite attribute Functional dependency Identifying relationship Table 3.2 9

11 STRUCTURED QUESTIONS (50 marks) INSTRUCTION: This section consists of THREE (3) structured questions. Answer ALL questions. QUESTION 4 1. Study the tables STUDENT, ENROLL and CLASS in Figure 4.1: STU_NUM STU_LNAME Bowser _10014_ STU_NUM c B A B c ENROLL_ GRADE CLASS_CODE CRS_CODE CLASS_SECTION CLASS_TIME CLASS_ROOM PROF_NUM I ACCT CIT THUR. 2: I MON. 9:00-9:5d BUS252 KLR Figure 4.1 i. ii. ii. iv) Determine primary key for each table Determine foreign keys for these tables Write suitable command to create a table called CLASS Give an explanation of what the following SQL statement will result in. [2] [2] (4] [6] SELECT employee_id, hire_date, MONTHS_BETWEEN (SYSDATE, hire_date) Months_hired, ADD_MONTHS (hire_date, 6) REVIEW, NEXT_DAY (hire_date, 'MONDAY'), LAST_DAY (hire_date) FROM Employees Where MONTHS BETWEEN (SYSDATE, hire_date) < 50; v) How would you select all the records from a table named 'Persons' where the value of the column "FirstName" starts with an "a" using SQL statement? [2] 10

12 QUESTION 5 a) Explain how the log file is a fundamental feature in any database recovery mechanism. [4] b) Identify THREE (3) DDL statements in SQL and the function of each statement c) Describe the terms below: [6] [4] i) Subquery ii) Column aliases QUESTION 6 Design an ER diagram for keeping track of information about votes taken in the U.S. House of Representatives during the two-year congressional session. The database needs to keep track of each U.S. state's Name (e.g. Texas, New York, California) and includes the region of the state (whose domain is {North East, Midwest, Southwest, West}). Each CONGRESSPERSON in the House of Representatives us described by their Name, and includes the District represented, the StartDate when they were first elected, and the political Party they belong to (whose domain is {Republican, Democrat, Independent, other}). The database keeps track of each BILL (i.e. proposed law), and includes the BiiiName, the DateONote on the bill, whether the bill PassedOrFailed (whose domain is {YES, NO}), and the sponsor (the congressperson(s) who sponsored - i.e., proposed -the bill). The database keeps track of how each congressperson voted on each bill (domain of vote attribute is {Yes, No, Abstain, Absent}). Draw an ER schema diagram for the above application. (State clearly any assumption you make.) [20] <<<<<<<<<< END >>>>>>> 11

Refresher: ER-modeling, logical relational model, dependencies. Toon Calders

Refresher: ER-modeling, logical relational model, dependencies Toon Calders toon.calders@ulb.ac.be Different Levels Conceptual level: ER-diagrams Logical level: Relations, attributes, schemas, primary