Question 1

Explain the representation of a many-to-many strong entity relationship in a relational database design.

Accepted Answer

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Question 2

For the M-O (parent mandatory,child optional)case,what action(s)should be taken to ensure minimum cardinality is maintained?
A)Define referential integrity constraint from child to parent
B)Make foreign key NOT NULL
C)Will require trigger or other application code
D)Both A and B are correct

Accepted Answer

To ensure minimum cardinality is maintained in the M-O case, we should define a referential integrity constraint from the child to parent and make the foreign key NOT NULL. This can be achieved by selecting both options A and B, which will enforce the relationship between the parent and child tables and prevent any child rows from existing without a corresponding parent row. This can ensure that the minimum cardinality is maintained as per the requirements of the business logic. Option C is not necessary to maintain minimum cardinality in this case, as it may depend on the specific requirements of the application being developed.

Question 3

When transforming an ID-dependent E-R data model relationship into a relational database design,the referential integrity constraints should allow ________.
A)parent updates to cascade
B)child updates to cascade
C)child deletes to cascade
D)Both A and B are correct

Accepted Answer

In an ID-dependent E-R data model, the child entity's existence depends on the parent entity. Therefore, when a parent is updated, the changes should cascade to maintain referential integrity.

Question 4

How are one-to-one recursive relationships addressed using the relational model?

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Question 5

A referential integrity constraint policy that guarantees that a row in a parent table always has a required entry in a child table ________.
A)is known as a minimum cardinality enforcement action
B)needs to be documented by the database development team
C)is enforced in most DBMS products
D)Both A and B are correct

Accepted Answer

A referential integrity constraint policy that guarantees that a row in a parent table always has a required entry in a child table is known as a minimum cardinality enforcement action. This policy needs to be documented by the database development team, and it is enforced in most DBMS products. Therefore, both option A and B are correct.

Question 6

Which of the following is not true about N:M recursive relationships?
A)Both foreign keys in the intersection table refer to the same table.
B)Since it is a recursive relationship,an intersection table is not needed.
C)The foreign keys in the intersection table can't refer to the same attribute in the parent table.
D)Both B and C are correct.

Accepted Answer

Both B and C are correct explanations for what is not true about N:M recursive relationships. An intersection table is indeed needed to resolve the many-to-many relationship, even in recursive relationships. Also, the foreign keys in the intersection table refer to the same entity but must represent different instances, hence they can refer to the same attribute in the parent table.

Question 7

Which of the following is not true of recursive relationships?
A)When the recursive relationship is M:N,an intersection table is created.
B)The rows of a single table can play two different roles.
C)Recursive relationships can be 1:1,1:N,or M:N relationships.
D)When the relationship is 1:N,a new table must be defined to represent the relationship.

Accepted Answer

When the recursive relationship is 1:N, a new table does not need to be defined to represent the relationship. Instead, the same table can be used with a foreign key referencing the primary key within the same table. Therefore, option D is the incorrect statement among the given options. A, B, C are true statements about recursive relationships.

Question 8

In a supertype-subtype structure,discriminator attributes ________.
A)are easily represented in a relational design
B)cannot be represented in a relational design
C)require application logic to determine which subtypes correspond to a specific supertype instance
D)Both B and C are correct

Accepted Answer

Discriminator attributes require application logic to determine which subtypes correspond to a specific supertype instance.

Question 9

The binary constraint must not indicates that ________.
A)a specific binary relationship must not be included in a ternary relationship
B)a table includes values that must not occur in a binary relationship
C)a table includes values that must not occur in a ternary relationship
D)a binary relationship includes value combinations that must not occur in a ternary relationship

Accepted Answer

A binary constraint specifies restrictions on the combinations of values that can appear in a binary relationship, and option D correctly describes this by stating that certain value combinations in a binary relationship must not occur in a ternary relationship.

Question 10

What are MUST NOT and MUST COVER constraints?

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Question 11

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 ________.
A)incremental updates
B)incremental deletes
C)cascading updates
D)cascading deletes

Accepted Answer

Cascading deletes ensure that when a row containing a primary key value in a parent table is deleted, all rows containing the corresponding foreign key value in child tables are also deleted. This helps maintain referential integrity in the database.

Question 12

The binary constraint must cover indicates that ________.
A)a specific binary relationship must be included in a ternary relationship
B)a binary relationship includes a set of value combinations that must all occur in a ternary relationship
C)a table includes values that must occur in a binary relationship
D)a table includes values that must occur in a ternary relationship

Accepted Answer

The binary constraint is a constraint that must be satisfied for a ternary relationship. It specifies a set of value combinations that must occur in a binary relationship between two entities that participate in the ternary relationship. Therefore, choice B is the correct answer. The other choices are incorrect because they either mention specific relationships or tables that may or may not be relevant to the binary constraint.

Question 13

When transforming an ID-dependent E-R data model relationship into a relational database design and the parent entity has a surrogate primary key and the child entity has a data identifier,then the primary key of the child table should be ________.
A)the parent's surrogate key + the child's data key
B)the parent's surrogate key + a surrogate key in the child
C)either A or B will work,but method A is preferable
D)either A or B will work,but method B is preferable

Accepted Answer

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Question 14

Explain the representation of a one-to-many strong entity relationship in a relational database design.

Accepted Answer

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Question 15

What is an association relationship and how does it differ from an N:M relationship?

Accepted Answer

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Question 16

Briefly describe the process of converting an extended E-R model into a relational database design.

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Question 17

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 ________.
A)incremental updates
B)incremental deletes
C)cascading updates
D)cascading deletes

Accepted Answer

Cascading updates is the referential integrity constraint policy that ensures that foreign key values in a table are correctly maintained when there is a change to the primary key value in the parent table. When a primary key value is updated, it is cascaded to all the corresponding foreign keys in the child tables, ensuring data consistency. Incremental updates and deletes are not relevant to this scenario, while cascading deletes can result in loss of data if not used carefully.

Question 18

Explain the pragmatic reason for using surrogate keys.

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Question 19

Which of the following is not true about representing subtypes in a relational database design?
A)One table is created for the supertype and one for each subtype.
B)All of the attributes of the supertype are added to the subtype relations.
C)The key of the supertype is made the key of the subtypes.
D)An instance of the supertype may be related to one instance each of several subtypes.

Accepted Answer

All of the attributes of the supertype should not be added to the subtype relations. Only the attributes that are common to all subtypes should be added to the supertype table, while the unique attributes of each subtype should be added to their respective tables.

Question 20

Which of the following is not true of MUST constraint?
A)It may be needed in ternary relationships to enforce special business rules.
B)It can be expressed directly in a relational model.
C)It must be enforced by program code.
D)It requires that one entity be combined with another entity.

Accepted Answer

MUST constraints, which are used to enforce certain business rules, cannot be directly expressed in the relational model. They typically require additional mechanisms, such as program code or triggers, to enforce the rules.

Quiz 6: Transforming Data Models Into Database Designs

Explain the representation of a many-to-many strong entity relationship in a relational database design.

For the M-O (parent mandatory,child optional) case,what action(s) should be taken to ensure minimum cardinality is maintained?

When transforming an ID-dependent E-R data model relationship into a relational database design,the referential integrity constraints should allow ________.

How are one-to-one recursive relationships addressed using the relational model?

A referential integrity constraint policy that guarantees that a row in a parent table always has a required entry in a child table ________.

Which of the following is not true about N:M recursive relationships?

Which of the following is not true of recursive relationships?

In a supertype-subtype structure,discriminator attributes ________.

The binary constraint must not indicates that ________.

What are MUST NOT and MUST COVER constraints?

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 ________.

The binary constraint must cover indicates that ________.

When transforming an ID-dependent E-R data model relationship into a relational database design and the parent entity has a surrogate primary key and the child entity has a data identifier,then the primary key of the child table should be ________.

Explain the representation of a one-to-many strong entity relationship in a relational database design.

What is an association relationship and how does it differ from an N:M relationship?

Briefly describe the process of converting an extended E-R model into a relational database design.

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 ________.

Explain the pragmatic reason for using surrogate keys.

Which of the following is not true about representing subtypes in a relational database design?

Which of the following is not true of MUST constraint?