Insy 3304 Chapter 3

13. The SELECT operator yields a vertical subset of a table. a. True b. False

ANSWER: False

15. In a natural join, the column on which the join was made occurs twice in the new table. a. True b. False

ANSWER: False

18. The one-to-many (1:M) relationship is easily implemented in the relational model by putting the foreign key of the "1" side in the table of the "many" side as a primary key. a. True b. False

ANSWER: False

3. The order of the rows and columns is important to the DBMS. a. True b. False

ANSWER: False

4. Character data can contain any character or symbol intended for mathematical manipulation. a. True b. False

ANSWER: False

5. The row's range of permissible values is known as its domain. a. True b. False

ANSWER: False

6. The idea of determination is unique to the database environment. a. True b. False

ANSWER: False

7. Only a single attribute, not multiple attributes, can define functional dependence. a. True b. False

ANSWER: False

1. The practical significance of taking the logical view of a database is that it serves as a reminder of the simple file concept of data storage. a. True b. False

ANSWER: True

10. Depending on the sophistication of the application development software, nulls can create problems when functions such as COUNT, AVERAGE, and SUM are used. a. True b. False

ANSWER: True

11. RDBMSs enforce integrity rules automatically. a. True b. False

ANSWER: True

12. Relational algebra defines the theoretical way of manipulating table contents using relational operators. a. True b. False

ANSWER: True

14. The DIFFERENCE operator subtracts one table from the other. a. True b. False

ANSWER: True

16. The DIVIDE operation uses one single-column table (e.g., column "a") as the divisor and one two-column table (e.g., columns "a" and "b") as the dividend. a. True b. False

ANSWER: True

17. A data dictionary is sometimes described as "the database designer's database" because it records the design decisions about tables and their structures. a. True b. False

ANSWER: True

19. As rare as 1:1 relationships should be, certain conditions absolutely require their use. a. True b. False

ANSWER: True

2. You can think of a table as a persistent representation of a logical relation. a. True b. False

ANSWER: True

20. Each table in a relational database must have a primary key. a. True b. False

ANSWER: True

8. If the attribute (B) is functionally dependent on a composite key (A) but not on any subset of that composite key, the attribute (B) is fully functionally dependent on (A). a. True b. False

ANSWER: True

9. A null is created when you press the Enter key or the Tab key to move to the next entry without making a prior entry of any kind. a. True b. False

ANSWER: True

44. The _____ relationship should be rare in any relational database design. a. 1:1 b. 1:M c. M:1 d. M:N

a. 1:1

34. _____ returns only the attributes requested, in the order in which they are requested. a. PROJECT b. SELECT c. UNION d. DIFFERENCE

a. PROJECT

21. _____ logic, used extensively in mathematics, provides a framework in which an assertion (statement of fact) can be verified as either true or false. a. Predicate b. Database c. Relational d. Index

a. Predicate

46. Another name for a composite entity is a(n) _____ entity. a. bridge b. linked c. directive d. associative

a. bridge

22. Each table _____ represents an attribute. a. column b. row c. dimension d. value

a. column

39. A _____ contains at least all of the attribute names and characteristics for each table in the system. a. data dictionary b. relational schema c. logical schema d. database

a. data dictionary

30. The CUSTOMER table's primary key is CUS_CODE. The CUSTOMER primary key column has no null entries, and all entries are unique. This is an example of _____ integrity. a. entity b. referential c. relational d. null

a. entity

29. Referential _____ dictates that the foreign key must contain values that match the primary key in the related table, or must contain null. a. integrity b. uniqueness c. model d. attribute

a. integrity

25. A _____ is any key that uniquely identifies each row. a. superkey b. special key c. foreign key d. candidate key

a. superkey

43. The _____ relationship is the "relational model ideal." a. 1:1 b. 1:M c. M:1 d. M:N

b. 1:M

31. The _____ constraint can be placed on a column to ensure that every row in the table has a value for that column. a. UNIQUE b. NOT NULL c. VALUE d. EMPTY

b. NOT NULL

37. _____ are especially useful when you are trying to determine what values in related tables cause referential integrity problems. a. Inner joins b. Outer joins c. Equijoins d. Theta joins

b. Outer joins

26. A _____ key can be described as a minimal superkey, a superkey without any unnecessary attributes. a. secondary b. candidate c. primary d. foreign

b. candidate

41. In a database context, the word _____ indicates the use of the same attribute name to label different attributes. a. redundancy b. homonym c. duplicate d. synonym

b. homonym

38. A(n) _____ only returns matched records from the tables that are being joined. a. outer join b. inner join c. equijoin d. theta join

b. inner join

24. In the relational model, _____ are important because they are used to ensure that each row in a table is uniquely identifiable. a. relations b. keys c. indexes d. logical structures

b. keys

49. According to Codd's _____ rule of relational database, "Application programs and ad hoc facilities are logically unaffected when changes are made to the table structures that preserve the original table values (changing order of columns or inserting columns)." a. nonsubversion b. logical data independence c. comprehensive data sublanguage d. integrity independence

b. logical data independence

35. When two or more tables share the same number of columns, and when their corresponding columns share the same or compatible domains, they are said to be _____. a. intersect-compatible b. union-compatible c. difference-compatible d. select-compatible

b. union-compatible

23. Date attributes contain calendar dates stored in a special format known as the _____ date format. a. Epoch b. calendar c. Julian d. logical

c. Julian

45. _____ relationships can be implemented by creating a new entity in 1:M relationships with the original entities. a. 1:N b. M:1 c. M:N d. 1:1

c. M:N

42. In a database context, a(n) _____ indicates the use of different names to describe the same attribute. a. entity b. duplicate c. synonym d. homonym

c. synonym

48. When you define a table's primary key, the DBMS automatically creates a(n) _____ index on the primary key column(s) you declared. a. key b. composite c. unique d. primary

c. unique

32. To be considered minimally relational, the DBMS must support the key relational operators _____, PROJECT, and JOIN. a. INTERSECT b. UNION c. DIFFERENCE d. SELECT

d. SELECT

33. _____, also known as RESTRICT, yields values for all rows found in a table that satisfy a given condition. a. INTERSECT b. UNION c. DIFFERENCE d. SELECT

d. SELECT

27. A _____ is the primary key of one table that has been placed into another table to create a common attribute. a. superkey b. composite primary key c. candidate key d. foreign key

d. foreign key

47. A(n) _____ is an orderly arrangement used to logically access rows in a table. a. primary rule b. superkey c. relationship d. index

d. index

36. A(n) _____ join links tables by selecting only the rows with common values in their common attribute(s). a. attribute b. unique c. foreign d. natural

d. natural

28. A _____ key is defined as a key that is used strictly for data retrieval purposes. a. lookup b. foreign c. candidate d. secondary

d. secondary

40. The _____ is actually a system-created database whose tables store the user/designer-created database characteristics and contents. a. database tuple b. systematic database c. unique index d. system catalog

d. system catalog