Deck 6: Developing Data Models for Business Databases

Question 1

When an optional 1-M relationship is converted into a new table,the new table contains foreign keys for the primary keys of both entity types participating in the relationship.

Answer 1

True

Question 2

To avoid null values in foreign keys,an optional 1-M relationship can be converted to a separate table.

Answer 2

True

Question 3

Design errors are more difficult to detect than diagram errors because they involve the meaning of the items on a diagram instead of just the structure of the diagram.

Answer 3

True

Question 4

Whenever an entity can exist in multiple states,a generalization hierarchy should be used.

Question 5

Identification dependency is required to transform a single entity type into two entity types and a relationship.

Question 6

One common refinement to an initial ERD would be to split compound attributes into smaller attributes.

Question 7

Both SQL:1999 and the Relational Model directly support generalization hierarchies.

Question 8

Converting an optional 1-M relationship into a table results in easier query formulation and faster query execution.

Question 9

In converting a generalization hierarchy in an ERD to a relational database design,the parent and the subtypes at every level each become a table.

Question 10

When converting a narrative problem into an ERD,which of the following would potentially be converted into an entity type:

A) Things
B) Places
C) Events
D) All of the above

Question 11

Primary keys for entity types:

A) Can be automatically generated by a DBMS
B) Should be single purpose
C) Are sometimes determined by industry or organizational practice
D) All of the above

Question 12

When adding historical details to a relationship,typically the 1-M relationship is converted to an M-N relationship with an attribute.

Question 13

One of the benefits of transforming an entity type into a generalization hierarchy is the avoidance of null values in entities.

Question 14

In order to make it easier to reference an entity type after conversion to a table,a weak entity is sometimes changed to a strong entity and the associated identifying relationships are changed to nonidentifying relationships.

Question 15

When a 1-1 relationship is converted into two foreign keys,if the relationship is optional for one of the entity types,the corresponding foreign key may be eliminated.

Question 16

When converting a narrative problem into an ERD,the narrative usually is a good source from which to derive relationships between entity types.

Question 17

In order to enforce referential integrity constraints when converting a generalization hierarchy,the ON DELETE CASCAED option should be specified for actions on referenced rows.

Question 18

The basic rules for converting an ERD cannot be applied to converting self-referencing relationships or more complex identification dependencies.

Question 19

An associative entity type should be used whenever combinations of three or more objects must be recorded.

Question 20

A primary key for an entity type should never change after it has been assigned,and it should serve no other purpose but to identify that entity.

Question 21

Figuer:
Assuming that we do not use the rule(s)that avoid null values in tables,converting the ERD diagram to a relational database will produce the following number of tables:

A) 3
B) 4
C) 5
D) 6

Question 22

Redundant relationships in a database design:

A) Can be derived from other relationships
B) Cannot be identified by reviewing the ERD
C) Should always be removed from the database design
D) None of the above

Question 23

Which of the following ERD conversion rules should be applied before the others:

A) 1-M Relationship Rule
B) M-N Relationship Rule
C) Identification Dependency Rule
D) Generalization Hierarchy Rule

Question 24

Figuer:
The table WRITTEN-BY obtained in converting the ERD diagram to a relational database will contain the following number of attributes:

A) 3
B) 4
C) 5
D) 6

Question 25

Figuer:
In converting the ERD diagram to a relational database,SS# will appear as a foreign key the following number of times:

A) 3
B) 4
C) 5
D) 6

Question 26

A common design problem in an ERD might be:

A) Inappropriate use of generalization hierarchies
B) Missing or misplaced relationships
C) Inappropriate use of M-way relationships
D) All of the above

Question 27

Design documentation:

A) Should explain subtle design decisions
B) Should describe incompleteness and inconsistency in specification requirements
C) Should communicate the database design to other interested parties throughout the lifetime of the database
D) All of the above

Question 28

One example of splitting compound entity type attributes into smaller attributes would be:

A) Splitting a customer's name into last name and first name
B) Splitting a customer's address into street, city, state and zip code
C) Both A and B
D) Neither A or B

Question 29

Figuer:
Converting the ERD diagram to a relational database will produce the following number of tables:

A) 3
B) 4
C) 5
D) 6

Question 30

Figuer:
Assuming that we use the rule(s)that avoid null values in tables,the table AUTHOR obtained in converting the ERD diagram to a relational database will have the following number of attributes:

A) 2
B) 3
C) 4
D) 5

Question 31

Figuer:
Assuming that we do not use the rule(s)that avoid null values in tables,the table VOLUME obtained in converting the ERD diagram to a relational database will have the following primary key:

A) Volume#
B) Title
C) Combination Volume#, Title
D) Combination Volume#, Title, #-of-pages

Question 32

Figuer:
In converting the ERD diagram to a relational database,SS# will appear in the following number of tables:

A) 3
B) 4
C) 5
D) 6

Question 33

Figuer:
Assuming that we do not use the rule(s)that avoid null values in tables,the table AUTHOR obtained in converting the ERD diagram to a relational database will have the following number of attributes:

A) 2
B) 3
C) 4
D) 5

Question 34

In data modeling:

A) More than one alternative may exist for a user requirement
B) Additional information from users is usually needed in order to evaluate alternatives
C) The process is usually iterative or repetitive
D) All of the above

Question 35

Figuer:
Assuming that we do not use the rule(s)that avoid null values in tables in converting the ERD diagram to a relational database,title will appear as a foreign key the following number of times:

A) 2
B) 3
C) 4
D) 5

Question 36

Figuer:
Assuming that we use the rule(s)that avoid null values in tables in converting the ERD diagram to a relational database,the number of tables will be:

A) 3
B) 4
C) 5
D) 6

Question 37

When constructing an ERD from a problem narrative:

A) You can derive relationships but not cardinalities from the narrative
B) You can derive cardinalities but not relationships from the narrative
C) You can usually derive both relationships and cardinalities from the narrative, but sometimes they are incomplete
D) None of the above

Question 38

Figuer:
The table WRITTEN-BY obtained in converting the ERD diagram to a relational database will have the following primary key:

A) Title
B) Combination Title, Aname
C) Aname
D) Combination Title, Aname, author-rank-in-book

Question 39

Figuer:
Assuming that we do not use the rule(s)that avoid null values in tables in converting the ERD diagram to a relational database:

A) Cname appears as a foreign key in the table Author
B) Cname may have null values in the table Author
C) Both of the above
D) None of the above

Question 40

Figuer:
Assuming that we do not use the rule(s)that avoid null values in tables,the table BOOK obtained in converting the ERD diagram to a relational database will contain the following number of attributes:

A) 3
B) 4
C) 5
D) 6

Question 41

Figuer:
In converting the ERD diagram to a relational database,"ON DELETE CASCADE" option is set in the following number of tables:

A) 3
B) 4
C) 5
D) 6

Question 42

During narrative problem analysis you should look for nouns that have additional sentences describing their properties.The properties often indicate _________ of entity types.

Question 43

For relationship ________,you should look at the number (singular or plural)of nouns along with other words that indicate cardinality.

Question 44

Single purpose means that a primary key attribute should have no purpose other than ____________.

Question 45

Figuer:
In converting the ERD diagram to a relational database,SS# will appear as a key attribute the following number of times:

A) 3
B) 4
C) 5
D) 6

Question 46

Figuer:
Assuming that we do not use the rule(s)that avoid null values in tables in converting the ERD diagram to a relational database,the number of attributes in the primary key of the table SUBCOMMITTEE is:

A) 3
B) 4
C) 5
D) 6

Question 47

In a narrative,you should look for _________ involving people,things,places,and events as potential entity types.

Question 48

When performing the identification of primary keys,ideally,primary keys should be _______ and _________.

Question 49

In object-oriented modeling,which is defined first:

A) Objects
B) Classes
C) Features of objects
D) Interaction among objects

Question 50

The Unified Modeling Language:

A) Emphasizes processes rather than objects
B) Has supported generalization since its inception
C) Is the standard notation for object-oriented modeling
D) Both B and C

Question 51

Figuer:
Assuming that we do not use the rule(s)that avoid null values in tables in converting the ERD diagram to a relational database,Deptno appears as a foreign key the following number of times:

A) 3
B) 4
C) 5
D) 6

Question 52

In the absence of indication of minimum cardinality,the default should be _________.

Question 53

Figuer:
Assuming that we do not use the rule(s)that avoid null values in tables in converting the ERD diagram to a relational database,the number of tables will be:

A) 3
B) 4
C) 5
D) 6

Question 54

Stable means that a primary key should ___________ after it has been assigned to an entity.

Question 55

What statement is true regarding the various ERD notations:

A) Expression of cardinalities vary widely
B) Symbols for entity types may be different
C) Rules may vary
D) All of the above

Question 56

Figuer:
Assuming that we do not use the rule(s)that avoid null values in tables in converting the ERD diagram to a relational database,the number of attributes in the key of the table MEMBER is:

A) 3
B) 4
C) 5
D) 6

Question 57

The goals of narrative problem analysis are to strive for a _________ design that is __________ with the narrative.Be prepared to follow up with additional requirements collection and consideration of alternative designs.

Question 58

Relationships often appear as ________ connecting nouns previously identified as entity types.

Question 59

Figuer:
In converting the ERD diagram to a relational database,the table RN has the following number of attributes:

A) 3
B) 4
C) 5
D) 6

Question 60

When performing narrative problem analysis,besides identifying primary keys,you should also identify other ____________ (candidate keys).

Question 61

Design decisions to enforce uniqueness of attributes,attribute value restrictions,null values,and default values are efforts to in the design process to capture __________.

Question 62

Design errors are more difficult to detect and resolve than ____________ because design errors involve the meaning of elements on a diagram,not just a diagram's structure.

Question 63

One type of transformation that should be used sparingly,because it is a specialized modeling tool,is the transformation of an entity type into a ___________________.

Question 64

When refining a data model,__________ attributes (attributes that contain multiple kinds of data)should be split into smaller attributes.

Question 65

________________ should include justification for design decisions involving multiple feasible choices and explanations of subtle design choices.

Question 66

In converting an ERD into a set of relational table specifications the M-N Relationship Rule specifies that each M-N relationship becomes a separate table.The primary key of the table is a combined key consisting of the ________ of the entity types participating in the M-N relationship.

Question 67

Even if you create design documentation and perform checks for design errors during the design process,you will still need to conduct _______________ to ensure adequate design documentation and lack of design errors.

Question 68

In refining a data model,you should generate ______________ and evaluate them according to user requirements.

Question 69

A common design error is to leave relationships in a design that could be derived from other relationships.These relationships are referred to as ___________ relationships.

Question 70

The Identification Dependency Rule states that each identifying relationship (denoted by a solid relationship line)adds a component to the __________ of the weak entity.

Question 71

One important reason for documenting design decisions it to _______________ those decisions to others.

Question 72

A common refinement of a data model is to transform an _________ into an entity type.This is useful when the database should contain more than just the identifier of an entity.

Question 73

A common design error that occurs when you do not consider all of the queries that a database should support is to omit relationships between entities that map an important business rule.These omitted relationships are known as ______________.

Question 74

Repeating the information already contained in an ERD is an example of poor________________.

Question 75

During the iterative design of an ERD,two important aspects of the specification should be documented as they are discovered so that they can be resolved through more extensive requirements gathering.They are inconsistency and ___________ in the specification.