Deck 6: Transforming Data Models Into Database Designs

Question 1

A surrogate key is a unique,system-supplied identifier used as the primary key of a table.

Answer 1

True

Question 2

An entity needs to be examined according to normalization criteria before creating a table from it in the relational database design.

Answer 2

False

Question 3

By default,the identifier of the entity becomes the foreign key of the corresponding table.

Answer 3

False

Question 4

When creating a relational database design from E-R diagrams,first create a relation for each relationship.

Question 5

Each entity in the extended E-R model is represented as a table in the relational database design.

Question 6

The last step in creating a table is to verify table normalization.

Question 7

A surrogate key is appropriate when the primary key of a table contains a lengthy text field.

Question 8

A surrogate key should be considered when the key contains a lengthy text field.

Question 9

A null value is an attribute value that has been set to zero.

Question 10

When creating a table in the relational database design from an entity in the extended E-R model,the attributes of the entity become the rows of the table.

Question 11

The values of a surrogate key have no meaning to the users.

Question 12

One of the important properties of a column is whether or not it can have a NULL value.

Question 13

Data types are consistent across all DBMS products.

Question 14

Whether or not an attribute is required is determined during the database modeling phase.

Question 15

A foreign key is a key that does not belong in any table.

Question 16

The first step in the database design process is to create tables and columns from entities and attributes.

Question 17

A data constraint is a limitation on data values.

Question 18

A default value is the value the user enters into the row the first time the user enters data.

Question 19

One of the important properties of an attribute is whether or not it is required.

Question 20

The ideal primary key is short,numeric,and fixed.

Question 21

To represent an N:M relationship in a relational database design,in essence it is reduced to two 1:N relationships.

Question 22

To represent a 1:N relationship in a relational database design,an intersection table is created.

Question 23

To represent an N:M relationship in a relational database design,an intersection table is created.

Question 24

An intersection table can have additional attributes besides the keys of its parent tables.

Question 25

Like all ID-dependent relationships,the parents of an association table are required.

Question 26

An intersection table is always ID-dependent on both of its parent tables.

Question 27

To represent a 1:1 binary relationship in a relational database design,the key of one table is placed into the second table.

Question 28

In a 1:1 relationship,the foreign key is defined as an alternate key to make the DBMS enforce uniqueness.

Question 29

In a relational database design,all relationships are expressed by creating a foreign key.

Question 30

When the key of one table is placed into a second table to represent a relationship,the key is called a relational key in the second table.

Question 31

In representing a 1:N relationship in a relational database design,the key of the table representing the entity on the "many" side is placed as a foreign key in the table representing the entity on the "one" side of the relationship.

Question 32

In a 1:N relationship,the term parent refers to the table on the "many" side of the relationship.

Question 33

In 1:N relationships,the table on the "one" side is called the parent.

Question 34

In representing a 1:N relationship in a relational database design,the key of the table representing the parent entity is placed as a foreign key in the table representing the child entity.

Question 35

In many-to-many relationships in a relational database design,the primary keys of both tables are joined into a composite primary key in the intersection table.

Question 36

When placing a foreign key for a 1:1 relationship,the key of either table can be used as the foreign key in the other table.

Question 37

To represent an N:M relationship in a relational database design,a table is created to represent the relationship itself.

Question 38

To represent a one-to-many relationship in a relational database design,the key of the child table is placed as a foreign key into the other table.

Question 39

A key of an intersection table is always the combination of the keys of both parents.

Question 40

In 1:N relationships,the table on the "many" side is called the child.

Question 41

When transforming an extended E-R model into a relational database design,recursive relationships are treated fundamentally the same as other HAS-A relationships.

Question 42

All identifying relationships are 1:N.

Question 43

If the parent is required,then a new child row must be created with a valid foreign key value.

Question 44

Association tables sometimes connect more than two entities.

Question 45

Cascading deletions are generally not used with relationships for weak child entities.

Question 46

When creating a table for an ID-dependent entity,both the key of the parent and the key of the entity itself must appear in the table.

Question 47

When transforming supertype/subtype entities into a relational database design,an entity is created for the supertype only.

Question 48

When transforming supertype/subtype entities into a relational database design,the key of the supertype table is placed into the subtype table typically as the key.

Question 49

Discriminator attributes can be represented in relational designs.

Question 50

When the parent entity is required (M)in a relationship,every row of the child table must have a valid,non-null value of the foreign key.

Question 51

Referential integrity constraints should disallow adding a new row to a child table when the foreign key does not match a primary key value in the parent table.

Question 52

Recursive M:N relationships are represented with an intersection table that shows pairs of related rows from a single table.

Question 53

A referential integrity constraint policy that insures that foreign key values in a table are correctly maintained when there is a change to the primary key value in the parent table is called cascading insertions.

Question 54

When transforming an ID-dependent E-R data model relationship into a relational database design where the child entity is designed to use a surrogate key,the relationship changes to a weak but not ID-dependent relationship.

Question 55

To represent an IS-A relationship in a relational database design,the IS-A relationship must be converted into a HAS-A relationship.

Question 56

Cascading deletions are generally not used with relationships between strong entities.

Question 57

A referential integrity constraint policy that insures that all rows containing a particular foreign key value in a table are eliminated from the table when the row containing the corresponding primary key value in a parent table is eliminated from the database is called cascading deletes.

Question 58

An ID-dependent table can be used to represent multivalued attributes.

Question 59

When transforming supertype/subtype entities into a relational database design,all of the attributes for the supertype table are placed into the subtype relations.

Question 60

The design transformation for all IS-A relationships can be summarized by the phrase "place the key of the parent table in the child table."

Question 61

Which of the following is not true about a NULL attribute?

A)On insertion,entering the data for that field is optional.
B)It is an important property of an attribute.
C)It must have a default value specified.
D)A primary key can't be NULL.

Question 62

It is easy to enforce the referential integrity actions for M-M relationships.

Question 63

Many-to-many relationships are represented by ________.

A)two tables with an M:N relationship
B)two tables with a 1:N relationship
C)an intersection table which has M:N relationships with the two tables
D)an intersection table which has 1:N relationships with the two tables

Question 64

When transforming an E-R data model into a relational database design,the key of the parent entity should be placed as part of the primary key into the child entity ________.

A)when the child entity is ID-dependent
B)when the child entity is non-ID-dependent
C)when the child entity has a 1:1 relationship with the parent entity
D)when the child entity has a 1:N relationship with the parent entity

Question 65

When the parent entity has a surrogate key,the enforcement actions are the same for both parent and child.

Question 66

When the child entity is required (M)in a relationship,there needs to be at least one child row for each parent row at all times.

Question 67

Each attribute of an entity becomes a(n)________ of a table.

A)column
B)primary key
C)foreign key
D)alternate key

Question 68

In many-to-many relationships in a relational database design,________.

A)the key of the child is placed as a foreign key into the parent
B)the key of the parent is placed as a foreign key into the child
C)the keys of both tables are placed in a third table
D)the keys of both entity tables are placed in each other

Question 69

A surrogate key should be considered when ________.

A)A relationship is N:M
B)A composite key is required
C)The key contains a lengthy text field
D)The key contains a number

Question 70

When representing a 1:1 relationship in a relational database design,________.

A)the key of each table must be placed as foreign keys into the other
B)the key of either table may be placed as a foreign key into the other
C)the key of both tables must be the same
D)the intersection table gets the key from both relations

Question 71

The identifier of the entity becomes the ________ of the corresponding table.

A)primary key
B)foreign key
C)supertype
D)subtype

Question 72

When representing a one-to-many relationship in a relational database design,________.

A)the parent is always on the one side of the "one-to-many" relationship
B)the child is always on the one side of the "one-to-many" relationship
C)either parent or child can be on the one side of the "one-to-many" relationship,and the choice is arbitrary
D)either parent or child can be on the one side of the "one-to-many" relationship,and special criteria indicate which table should be on the one side

Question 73

In relational database design,ID-dependent entities are not used to ________.

A)represent N:M relationships
B)handle associative relationships
C)represent relationships where the child identifier does not include the key of the parent
D)handle archetype/instance relationships

Question 74

Which of the following is not true for an ideal primary key?

A)a composite of several long attributes
B)numeric
C)fixed
D)short

Question 75

In many-to-many relationships between strong entities in a relational database design,which of the following is not true?

A)The intersection table is ID-dependent on one of the parents
B)The intersection table is ID-dependent on both of the parents
C)The relationships from the intersection table to the parent tables are identifying relationships
D)The maximum cardinality to the intersection table is always N

Question 76

Which of the following is not true about surrogate keys?

A)They are identifiers that are supplied by the system,not the users.
B)They have no meaning to the users.
C)They are non-unique within a table.
D)They can be problematic when combining databases.

Question 77

The first step in transforming an extended E-R model into a relational database design is to ________.

A)create a table for each relationship
B)evaluate the entities against the normalization criteria
C)create a table for each entity
D)remove any recursive relationships

Question 78

To represent a one-to-many relationship in a relational database design,________.

A)the key of the child is placed as a foreign key into the parent
B)the key of the parent is placed as a foreign key into the child
C)an intersection table must be created
D)the key of the table on the "many" side is placed in the table on the "one" side

Question 79

In a relational database design,all relationships are expressed by ________.

A)creating a primary key
B)creating a foreign key
C)creating a supertype
D)creating a subtype

Question 80

Which of the following is not a step in the database design process?

A)Create tables and columns from entities and attributes
B)Select primary keys
C)Represent relationships
D)Create constraints and triggers