Review Modelling C1 TO 6 PDF

Preview

Summary

Practice Modeling ...

Description

Review-Modelling Based on Chapters 1 – 6. True/False: Indicate whether the statement is true or false.

____

1. The focus on effective Internet interfacing makes the underlying data model more important to the end user.

____

2. A data dictionary contains metadata—data about data.

____

3. The Crow’s Foot model is less implementation-oriented than the Chen model.

____

4. Normalization is a very important database design ingredient and the highest level is always the most desirable.

____

5. Relational models view the data as part of a table or collection of tables in which all key values must be identified.

____

6. An entity cluster is a "virtual" entity type used to represent multiple entities and relationships in the ERD.

Multiple Choice Identify the choice that best completes the statement or answers the question.

____

____

____

7. Which of the following is a basic building block of all data models? a. category

c. constraint

b. class

d. customer

8. The hierarchical data model was developed in the ____. a. 1960s

c. 1980s

b. 1970s

d. 1990s

9. The relational data model was developed in the ____. a. 1960s

c. 1980s

b. 1970s

d. 1990s

____ 10. VMS/VSAM is an example of a(n) ____. a. hierarchical model

c. relational data model

b. file system data model

d. XML data model

____ 11. Oracle 10g is an example of a(n) ____. a. hierarchical model

c. relational data model

b. file system data model

d. XML data model

____ 12. MySQL is an example of a(n) ____. a. hierarchical model

c. relational data model

b. file system data model

d. XML data model

____ 13. One of the limitations of the ____ model was that there were no implementation standards. a. hierarchical

c. relational

b. network

d. entity relationship

____ 14. In the ____ model, the user perceives the database as a collection of records in 1:M relationships, where each record can have more than one parent. a. hierarchical

c. object-oriented

b. network

d. entity relationship

____ 15. The ____ model is said to be a semantic data model. a. relational

c. object-oriented

b. network

d. entity relationship

____ 16. Which data model has the highest level of abstraction? a. Object-oriented

c. Relational

b. Entity relationship

d. Hierarchical

____ 17. ____ 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

c. Relational

b. Database

d. Index

____ 18. The relational database model enables you to view data ____ rather than ____. a. relationally, hierarchically

c. physically, logically

b. hierarchically, relationally

d. logically, physically

____ 19. The relational model’s creator, E. F. Codd, used the term relation as a synonym for ____. a. index

c. table

b. key

d. relationship

____ 20. ____ data can have only a true or false (yes or no) condition. a. Logical

c. Date

b. Character

d. Numeric

____ 21. No data entry at all is known as a(n) ____. a. nil

c. empty

b. null

d. zero

____ 22. Controlled ____ makes a relational database work. a. relations

c. chaos

b. logic

d. redundancy

____ 23. ____ yields only the rows that appear in both tables. a. INTERSECT

c. DIFFERENCE

b. UNION

d. SELECT

____ 24. ____, also known as RESTRICT, yields values for all rows found in a table that satisfy a given condition. a. INTERSECT

c. DIFFERENCE

b. UNION

d. SELECT

____ 25. A(n) ____ join links tables by selecting only the rows with common values in their common attribute(s). a. equal

c. foreign

b. unique

d. natural

____ 26. The equijoin takes its name from the comparison operator ____ used in the condition. a. *

c. =

b. <

d. >

____ 27. In an outer join, the matched pairs would be retained and any unmatched values in the other table would be left ____. a. in another table b. null c. out of the results d. with matching values from the original table ____ 28. The ____ is actually a system-created database whose tables store the user/designer-created database characteristics and contents. a. meta dictionary

c. data dictionary

b. schema

d. system catalog

____ 29. The ____ relationship should be rare in any relational database design. a. 1:1

c. M:1

b. 1:M

d. M:N

____ 30. 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

c. unique

b. incomplete

d. primary

____ 31. Codd’s rule of ____ states: 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 column or inserting columns). a. Nonsubversion

c. Comprehensive Data Sublanguage

b. Logical Data Independence

d. Integrity Independence

____ 32. The ERD is used to graphically represent the ____ database model. a. condensed

c. logical

b. physical

d. conceptual

____ 33. A ____ attribute can have only one value. a. composite

c. single-valued

b. simple

d. multivalued

____ 34. A ____ might be represented with a multivalued attribute. a. Person’s name

c. Bank account balance

b. Household phone numbers

d. Book title

____ 35. The ____ type of attribute cannot be created in a DBMS. a. derived

c. simple

b. multivalued

d. composite

____ 36. A derived attribute ____. a. must be stored physically within the database b. need not be physically stored within the database c. has many values d. must be based on the value of three or more attributes ____ 37. A derived attribute is indicated in the Chen model by a ____. a. Single line

c. Circle

b. Dashed line

d. Double line

____ 38. Another word for existence-independent is ____. a. weak

c. unary

b. alone

d. strong

____ 39. When the PK of one entity does not contain the PK of a related entity, the relationship is ____.

a. missing

c. strong

b. weak

d. neutral

____ 40. If an entity can exist apart from one or more related entities, it is said to be ____-independent. a. existence

c. business

b. relationship

d. weak

____ 41. A ____ entity has a primary key that is partially derived from the parent entity in the relationship. a. strong

c. business

b. weak

d. relationship

____ 42. The Crow’s foot symbol with two parallel lines indicates ____ cardinality. a. (0,N)

c. (1,1)

b. (1,N)

d. (0,1)

____ 43. If an employee within an EMPLOYEE entity has a relationship with itself, that relationship is known as a ____ relationship. a. self

c. looping

b. self-referring

d. recursive

____ 44. A ____ relationship exists when three entities are associated. a. unary

c. ternary

b. binary

d. weak

____ 45. ____ relationships are most common. a. Unary

c. Ternary

b. Binary

d. Higher-degree

____ 46. Complex ____ requirements may dictate data transformations, and they may expand the number of entities and attributes within the design. a. information

c. design

b. entity

d. processing

____ 47. Converting a ____ is not an example of denormalization. a. 3NF to 2NF

c. 3NF to 1NF

b. 2NF to 1NF

d. 3NF to BCNF

____ 48. A relation is not in 1NF if ____. a. it has multiple candidate keys b. all of the key attributes are defined

c. there are repeating groups in the table d. all attributes are dependent on the primary key ____ 49. A(n) ____ should not be placed in a relational table. a. entity

c. relationship

b. attribute

d. repeating group

____ 50. In a(n) ____ diagram, the arrows above the attributes indicate all desirable dependencies. a. Chen

c. functionality

b. dependency

d. ER

____ 51. If you have three different transitive dependencies ____ different determinant(s) exist. a. one

c. three

b. two

d. four

____ 52. Improving ____ leads to more flexible queries. a. atomicity

c. denormalization

b. normalization

d. derived attributes

____ 53. For most business transactional databases, we should normalize relations into ____. a. 1NF

c. 3NF

b. 2NF

d. 6NF

____ 54. To generate a surrogate key, Microsoft Access uses a(n) ____ data type. a. surrogate

c. AutoNumber

b. sequence

d. identity

____ 55. BCNF can be violated only if the table contains more than one ____ key. a. primary

c. foreign

b. candidate

d. secondary

____ 56. A table is in 4NF if ____. a. all attributes must be dependent on the primary key, and must be dependent on each other b. all attributes are unrelated c. no row can contain two or more multivalued facts about an entity. d. no column contains the same values ____ 57. When designing a database, you should ____. a. make sure entities are in normal form before table structures are created b. create table structures then normalize the database

c. only normalize the database when performance problems occur d. consider more important issues such as performance before normalizing ____ 58. The conflicts between design efficiency, information requirements, and processing speed are often resolved through ____. a. conversion from 1NF to 2NF b. conversion from 2NF to 3NF c. compromises that include denormalization d. conversion from 3NF to 4NF ____ 59. ____ is a generic entity type that is related to one or more entity subtypes. a. A subtype discriminator

c. A specialization hierarchy

b. Inheritance

d. An entity supertype

____ 60. Every subtype can have ____ supertype(s) to which it is directly related. a. zero

c. one or many

b. only one

d. many

____ 61. In the specialization hierarchy there is a ____ relationship between a subtype and supertype. a. self-referring

c. 1:M

b. 1:1

d. M:N

____ 62. A(n) ____ is the attribute in the supertype entity that determines to which entity subtype each supertype occurrence is related. a. subtype discriminator

c. specialization hierarchy

b. inheritance discriminator

d. entity supertype

____ 63. The “____” characteristic of a primary key states that: The PK must uniquely identify each entity instance. A primary key must be able to guarantee unique values. It cannot contain nulls. a. unique values

c. preferably single-attribute

b. nonintelligent

d. security complaint

____ 64. The “____” characteristic of a primary key states that: The PK should not have embedded semantic meaning. An attribute with embedded semantic meaning is probably better used as a descriptive characteristic of the entity rather than as an identifier. a. unique values

c. preferably single-attribute

b. nonintelligent

d. security complaint

____ 65. ____ keys work with primary keys to properly implement relationships in the relational model. a. Foreign

c. Natural

b. Composite

d. Surrogate

____ 66. The preferred placement for a foreign key when working with a 1:1 relationship is ____. a. Use the same primary key for both entities b. Create a bridge entity c. Place a foreign key in one of the entities d. Place a foreign key in both entities

Essay

67. What do business rules require to be effective? 68. What are the sources of business rules, and what is the database designer’s role with regard to business rules? 69. Described the three parts involved in any SQL-based relational database application. 70. Describe a conceptual model and its advantages. What is the most widely used conceptual model? 71. Describe the use of nulls in a database. 72. Explain the difference between simple and composite attributes. Provide at least one example of each. 73. What is a ternary relationship? Provide some example business rules that specify the need for a ternary or higher-order relationship. 74. Explain normalization and its different forms. 75. What steps are involved in the conversion to third normal form? 76. Explain the BCNF. How is it related to other normal forms? 77. Explain the “no change over time” characteristic of a good primary key. 78. In what two cases are composite primary keys particularly useful...