Database management and theory exam 2 (chapter 6 MC questions)

9. In a given table, attribute Y is said to have what type of dependency on a set of attributes (X), if and only if, each X value is associated with precisely one Y value (X â†' Y)? A. Complete dependency B. Functional dependency C. Partial dependency D. Transitive dependency

ANS. B. Functional dependency

10. Which functional dependency types is/are not present in the following dependencies? Empno -> EName, Salary, Deptno, DName DeptNo -> DName EmpNo -> DName A. Full functional dependency B. Partial functional dependency C. Transitive functional dependency D. Both B and C

Ans : B. partial functional dependency Explanation: Partial functional dependency type is not present. Partial Dependency occurs when a non-prime attribute is functionally dependent on part of a candidate key. The 2nd Normal Form (2NF) eliminates the Partial Dependency. In the relation, StudentProject [StudentID (PK), ProjectNo (PK), StudentName, ProjectName], there are 2 partial functional dependencies. StudentName can be determined by StudentID, which makes the relation Partially Dependent.

11. If one attribute is determinant of second, which in turn is determinant of third, then the relation cannot be: A. Well-structured B. 1NF C. 2NF D. 3NF

Ans : D. 3NF transitive relationship exists. A transitive dependency is an indirect relationship between values in the same table that causes a functional dependency.

4. If attribute A determines both attributes B and C, then it is also true that: a. A --> B. b. B --> A. c. C --> A. d. (B,C) --> A.

Ans. a. A--> B

5. One solution to the multivalued dependency constraint problem is to: a. split the relation into two relations, each with a single theme. b. change the entity. c. Create a new theme. d. add a composite key.

Ans. a. split the relation into two relations, each with a single theme

6. A function that has no partial functional dependencies is in _______ form : a. 3NF b. 2NF c. 4NF

Ans. b. 2NF

2. For some relations, changing the data can have undesirable consequences called: a. referential integrity constraints b. modification anomalies c. normal forms d. transitive dependencies

Ans. b. modification anomalies

3. If attributes A and B determine attribute C, then it is also true that: a. A --> C. b. B --> C. c. (A,B) is a composite determinant. d. C is a determinant.

Ans. c. (A,B) is a composite determinant

9. Which of the following is not a restriction for a table to be a relation? a) The cells of the table must contain a single value b) All of the entries in any column must be of the same kind c) The columns must be ordered d) No two rows in a table may be identical

Ans. c. the columns must be ordered

1.A functional dependency is a relationship between or among: a. tables b. rows c. relations d. attributes

Ans. d. attributes

7. A relation is in 3NF if it is in 2NF and if it has no ____________ a) Functional Dependencies b) Transitive Dependencies c) Trivial Functional Dependency d) Multivalued Dependencies

Answer: b. Transitive Dependencies Explanation: For a relation to be in Third Normal Form, it must be in Second Normal form and the following must be satisfied: No non-prime attribute is transitively dependent on the primary key attribute.

8. A ___________ is an indirect functional dependency, one in which X->Z only by virtue of X->Y and Y->Z. a) Multivalued Dependency b) Join Dependency c) Trivial Functional Dependency d) Transitive Dependency

Answer: d. transitive dependency Explanation: Third Normal Form deals with something called "transitive" dependencies. This means if we have a primary key A and a non-key domain B and C where C is more dependent on B than A and B is directly dependent on A, then C can be considered transitively dependent on A.

16. What is a recursive foreign key? A. An attribute (or combination of attributes) that uniquely identifies a row in a relation B. It is a foreign key in a relation that references the primary key values of that same relation C. It is a primary key whose value is a serial number or other system assigned value and is unique to the relation D. It is a repeated primary or natural key that contains more than one attribute

ANS. B. It is a foreign key in a relation that references the primary key values of that same relation p. 146 The key of a table which acts as a primary key of some another table. The recursive foreign key is the key which refers back to the same table

17. What is a synonym for tuple in a relational database? A. Relational instance B. Row C. A and B

ANS. B. Row

7. What is database normalization? A. Elimination of insertion, addition, and deletion anomalies with constraints B. A process of organizing the relations, e.g., the fields and tables, to minimize redundancy and dependency C. A process of structuring data so it can be queried and manipulated using Structured Query Language (SQL)

ANS. B. a process of organizing the relations, e.g. the fields and tables, to minimize redundancy and dependency

11. When is a relation in first normal form? A. When all non-key columns are dependent on the table's primary key and are multivalued B. When each column contains atomic values, and there are no repeating groups of columns C. When every non-key attribute provide a fact about the key, the whole key, and nothing but the key

ANS. B. when each column contains atomic values, and there are no repeating groups of columns

10. What value can be used to identify a unique row in a table or tuple? A. Alternate key B. Foreign key C. Primary key D. Relational identifier

ANS. C. Primary key

13. Which of the following relations is an example of the recommended reduced set notation? A. Advisor {Advisor_ID, Name} B. SCHEDULE [FK_StudentNum, FK_CourseID] C. STUDENT [StudentNum(PK), StudFName, StudLName, Advisor_ID(FK), MajorID(FK)] D. STUDENT [StudentNum(PK), FK_Advisor_ID, MajorID(FK)]

ANS. C. STUDENT [StudentNum(PK), StudentFName, StudLName, Advisor_ID(FK), MajorID(FK)]

15. What is a domain? A. The base relations that store data B. The set of elements common to all data sets C. The set of possible values for a given attribute

ANS. C. The set of possible values for a given attribute p. 149

5. What is the term for a specific set of named and typed values? A. A relation schema B. A relationship C. A relvar D. A tuple

ANS. D. A Tuple

4. What is a commonly discussed benefit of building a logical data model? A. It helps avoid data redundancy B. It provides a foundation for designing a physical database C. It tells a compelling story of the data D. A and B E. B and C

ANS. D. A and B

3. What do we call a collection of descriptions of data objects or data items? A. A data dictionary B. A directory C. A metadata repository D. A and C. E. All of the above

ANS. D. A and C

1. What database model is the most common basis for creating a logical model? A. Hierarchical B. Network C. Object D. Relational

ANS. D. Relational

6. Generally, what is the first step in creating a Logical Data Model? A. Create relations for all associative entities B. Identify constraints, e.g., referential integrity. C. Resolve any supertype/subtype relationships. D. Specify primary keys for all entities.

ANS. D. Specify primary keys and all entities p. 134

18. If attribute X determines attribute Y, and attribute Y determines attribute Z, then what type of dependency exists between X and Z? A. Functional dependency B. Multivalued dependency C. Partial dependency D. Transitive dependency

ANS. D. Transitive dependency The rule is essentially that A is a transitive dependency of C (A->C) if A is functionally dependent on B (A->B), and B is functionally dependent on C (B->C) but not on A (B not->A). A transitive dependency in a database is an indirect relationship between values in the same table that causes a functional dependency.

8. If a table contains multiple records with the same Employee ID and Employee Address, but with different skills. what error can/might occur when the employee moves? A. Addition anomaly B. Deletion anomaly C. Insertion anomaly D. Update anomaly

ANS. D. Update anomaly

Normalization Practice Quiz answers 9/29/2020

Normalization Practice Quiz answers 9/29/2020

14. How is a dependent or weak entity in an ERD transformed for an LDM? A. A new relation is created corresponding to the weak entity. B. A separate relation is created for the supertype and the weak entity C. A weak entity is transformed into a simple relation with simple attributes

ANS. A. A new relation is created corresponding to the weak entity p. 146

12. What is the term for an attribute in a table that you can use to determine the values assigned to other attribute(s) in the same row (tuple)? A. A candidate key B. A determinant C. A nonintelligent key

ANS. B. A determinant

2. Which of the following is NOT a feature of a logical data model? A. All attributes for each entity are specified B. All entities and relationships create a hierachy C. Foreign keys are specified D. Primary key for each entity is specified E. Relations are normalized

ANS. B. All entities and relationships create a hierachy

Ch 6 additional Quiz questions answers

Ch 6 additional Quiz questions answers