Question 1

The process of splitting or combining normalized relations into physical tables based on affinity of use of rows and fields best describes:

Accepted Answer

The process of combining normalized relations into physical tables is known as denormalization. This is done to improve database performance by reducing the number of table joins needed for query processing.

Question 2

A many-to-many relationship that associates certain items with their component items is called a:

Accepted Answer

A bill-of-materials structure is a many-to-many relationship that associates certain items with their component items. It is commonly used in manufacturing industries to track the components needed to produce a product. A binary structure is a one-to-one relationship between two entities, a binary relationship is a one-to-many or many-to-one relationship between two entities, and a ternary relationship is a many-to-many relationship between three entities.

Question 3

For a binary many-to-many relationship existing between entity types A and B:

Accepted Answer

In a binary many-to-many relationship, a separate relation C must be created, and its primary key is a composite key consisting of the primary key for each of the two entities in the relationship. This is known as the associative entity approach, and it helps to resolve the many-to-many relationship by introducing a third entity to represent the relationship between the two entities. This approach also ensures that the relationship between the two entities is properly maintained and can be queried efficiently. Therefore, option A is the best choice. Option B is incorrect because it implies that the many-to-many relationship can be resolved by designating the primary keys of relation A and relation B as functionally dependent attributes, which is not a valid solution. Option C is incorrect because it suggests that secondary keys can be used to establish the relationship, which would not provide a unique reference to each of the entities in the relationship. Option D is incorrect because it does not create a separate relation for the many-to-many relationship, which is necessary to maintain the integrity of the relationship.

Question 4

The index file organization:

Accepted Answer

The index file organization provides moderately fast random retrieval on the primary key. This is because the index is created on the primary key and allows for quick access to specific records based on that key value. However, retrieving records through an index can still be slower than sequential retrieval, and the speed will depend on factors such as the size of the file and the efficiency of the indexing algorithm.

Question 5

Merging relations is also referred to as:

Accepted Answer

Merging relations is commonly referred to as view integration, which involves combining different views or relations into a unified schema.

Question 6

A ________ is an attribute whose value is unique across all occurrences of a relation.

Accepted Answer

The answer of A ________ is an attribute whose value...

Question 7

A foreign key in a relation that references the primary key values of that same relation is referred to as a:

Accepted Answer

A foreign key that references the primary key values of the same table is called a recursive foreign key. This is because it creates a self-referencing relationship within the table.

Question 8

Two different names that refer to the same data item best defines:

Accepted Answer

Synonym refers to two different names that refer to the same data item in a database context.

Question 9

A table used to determine the location of rows in a file that satisfy some condition best describes:

Accepted Answer

An index is used to determine the location of rows in a file that satisfy some condition. It is a data structure that improves the speed of data retrieval operations on a database table. Option A (relation) refers to a table in a relational database. Option B (structure chart) refers to a diagram that shows the structure of a computer program. Option D (domain table) is not a commonly used term in database management.

Question 10

A special field value,distinct from 0,blank,or any other value,that indicates that the value for the field is missing or otherwise unknown best defines:

Accepted Answer

The special field value that indicates that the value for the field is missing or otherwise unknown is called a null value.

Question 11

A single name that is used for two or more different attributes best defines:

Accepted Answer

Homonyms are words that share the same spelling and pronunciation but have different meanings. Therefore, a single name that is used for two or more different attributes is best defined as a homonym.

Question 12

Relationships between instances of a single entity type are referred to as:

Accepted Answer

In a recursive relationship, instances of the same entity type are related to each other. For example, an employee may manage other employees who are also employees themselves. This is different from binary relationships, which involve two different entity types, and transitive relationships, which involve three or more entity types. Dependent relationships is not a commonly used term in entity relationship modeling.

Question 13

If a relationship exists among three or more entities,then:

Accepted Answer

When a relationship exists among three or more entities, a separate relation with a primary key that is the composite of the primary keys of each of the participating entities is created. This is known as a junction table, intersection table or a composite entity. This table contains foreign keys referencing the primary keys of the original entities to establish the relationship among them.

Question 14

Which of the following combines range and hash partitioning by first segregating data by ranges on the designated attribute and then within each of these partitions it further partitions by hashing on the designated attribute?

Accepted Answer

Composite partitioning combines multiple partitioning techniques, in this case, range and hash partitioning. The data is first separated into partitions based on the range of values in the designated attribute, and then within each of these partitions, further partitioning is done by hashing on the same attribute.

Question 15

For a unary M:N relationship:

Accepted Answer

In a unary M:N relationship, the entity type is modeled as one relation with a composite key, and a separate relation is created to represent the M:N relationship.

Question 16

A named set of rows and columns that specifies the fields in each row of the table best describes:

Accepted Answer

The answer of A named set of rows and columns...

Question 17

A field of data that can be used to locate a related field or row of data best describes:

Accepted Answer

A pointer is a field of data used to locate a related field or row of data. It is a value that points to the memory address of another value or object. It is commonly used in programming languages and data structures to navigate through data and access related information. Marker, field locator, and reference locator are not commonly used terms for this concept.

Question 18

"Create a relation with primary key and nonkey attributes" is the relational representation for which E-R structure?

Accepted Answer

The creation of a relation with primary key and nonkey attributes is a characteristic of a regular entity in the E-R structure. Regular entities have their own primary key attribute, which uniquely identifies each instance of the entity, along with additional nonkey attributes that provide additional information about the entity. Weak entities, on the other hand, do not have their own primary key attribute and rely on a foreign key relationship with a strong entity to determine their identity. Gerunds and IS-A relationships are not relevant to this concept of creating a relation with primary key and nonkey attributes.

Question 19

If an associative entity exists,then:

Accepted Answer

An associative entity represents a many-to-many relationship between two entities, and thus requires a separate relation C to be created. The primary key of relation C is a composite key consisting of the primary key for each of the two entities in the relationship. This approach helps to establish a clear and efficient relationship between the entities.

Question 20

When two 3NF relations are merged to form a single relation:

Accepted Answer

Merging two 3NF relations can result in transitive dependencies, where an attribute in one relation depends on another attribute in the same relation as well as an attribute in the other relation. This violates normalization rules and can lead to data anomalies. Therefore, it is important to carefully examine the resulting relation for transitive dependencies and resolve them through further normalization. The other options of creating weak entities or recursive relationships may occur in specific situations, but they are not as common as transitive dependencies. IS-A relationships are formed through inheritance and are not relevant to merging relations.

Quiz 9: Designing Databases