Chapter 04: Entity Relationship (ER) Modeling

FALSE

The entity relationship model (ERM) is dependent on the database type.

FALSE

The Crow's Foot notation is less implementation-oriented than the Chen notation.

TRUE

An entity in the entity relationship model corresponds to a table in the relational environment.

TRUE

In the entity relationship model, a table row corresponds to an entity instance.

TRUE

In the Chen and Crow's Foot notations, an entity is represented with a rectangle containing the entity's name.

TRUE

In the original Chen notation, each attribute is represented by an oval with the attribute name connected to an entity rectangle with a line.

FALSE

Software vendors have adopted the Chen representation because of its compact representation.

TRUE

A composite identifier is a primary key composed of more than one attribute.

FALSE

The Crow's Foot notation easily identifies multivalued attributes.

FALSE

Composite attributes make it easier to facilitate detailed queries.

TRUE

Connectivities and cardinalities are established by concise statements known as business rules.

FALSE

In Chen notation, there is no way to represent cardinality.

FALSE

In implementation terms, an entity is existence-dependent if it has a mandatory primary key.

FALSE

A weak relationship exists if the primary key of the related entity contains at least one primary key component of the parent entity.

TRUE

A weak entity has a primary key that is partially or totally derived from the parent entity in the relationship.

TRUE

In a 1:M relationship, to avoid the possibility of referential integrity errors, the data of the '1' side must be loaded first.

FALSE

Relationships between entities always operate in one direction.

FALSE

The existence of a mandatory relationship indicates that the minimum cardinality is 0 or 1 for the mandatory entity.

FALSE

Referential integrity and participation are both bidirectional, meaning that they must be addressed in both directions along a relationship.

TRUE

To implement a small database, a database designer must know the '1' and the 'M' sides of each relationship and whether the relationships are mandatory or optional.

conceptual

The entity relationship diagram (ERD) represents the _____ database as viewed by the end user.

UML

The _____ notation of entity-relationship modelling can be used for both conceptual and implementation modelling.

domain

A(n) _____ is the set of possible values for a given attribute.

one

Ideally, an entity identifier is composed of _____ attribute(s).

composite

A _____ attribute can be further subdivided to yield additional attributes.

simple

A _____ attribute is one that cannot be subdivided.

M:N

The conceptual model can handle _____ relationships and multivalued attributes.

dashed line

A derived attribute is indicated in the Chen notation by a _____ that connects the attribute and an entity.

derived

The decision to store _____ attributes in database tables depends on the processing requirements and the constraints placed on a particular application.

entities

A relationship is an association between _____.

Cardinality

_____ expresses the minimum and maximum number of entity occurrences associated with one occurrence of the related entity.

(min, max)

In the entity relationship diagram (ERD), cardinality is indicated using the _____ notation, where max is the maximum number of associated entities and min represents the minimum number of associated entities.

symbols

When the specific cardinalities are not included on the diagram in Crow's Foot notation, cardinality is implied by the use of _____.

entity

Knowing the minimum and maximum number of _____ occurrences is very helpful at the application software level.

existence

An entity is said to be _____-dependent if it can exist in the database only when it is associated with another related entity occurrence.

strong

If an entity can exist apart from all of its related entities, then it is existence-independent, and it is referred to as a(n) _____ entity.

weak

A _____ entity has a primary key that is partially or totally derived from the parent entity in the relationship.

optional

The existence of a(n) _____ entity indicates that its minimum cardinality is zero.

unary

A _____ relationship exists when an association is maintained within a single entity.

ternary

A _____ relationship exists when three entities are associated.

recursive

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

binary

To simplify the conceptual design, most higher-order relationships are decomposed into appropriate equivalent _____ relationships whenever possible.

M:N

The entity relationship model uses the associative entity to represent a(n) _____ relationship between two or more entities.

solid

When using the Crow's Foot notation, the associative entity is indicated by _____ relationship lines between the parents and the associative entity.

creating a detailed narrative of the organization's description of operations

The first step in building an entity-relationship diagram (ERD) is _____.

(1,1)

The Crow's foot symbol with two vertical parallel lines indicates _____ cardinality.

optional to

If Tiny College has some departments that are classified as 'research only' and do not offer courses, the COURSE entity of the college database would be _____ the DEPARTMENT entity.

high processing speeds

In organizations that generate large number of transactions, _____ are often a top priority in database design.

information

Complex _____ requirements may dictate data transformations, and they may expand the number of entities and attributes within the design.

iterative

Database design is a(n) _____ process based on repetition.

Attributes

_____ are characteristics of entities.

required

A(n) _____ attribute is an attribute that must have a value.

Identifiers

_____ are underlined in an ER diagram.

single-valued

A person's Social Security number would be an example of a(n) _____ attribute.

derived

A(n) _____ attribute need not be physically stored within the database.

classification

A relationship _____ is difficult to establish if only one side of the relationship is known.

minimum

When indicating cardinality, the first value represents the _____ number of associated entities.

primary key

The concept of relationship strength is based on how the _____ of a related entity is defined.

strong

A(n) _____ relationship is also known as an identifying relationship.

solid

The Crow's Foot notation depicts the strong relationship with a(n) _____ line between the entities.

existence

A weak entity must be _____-dependent.

rectangle

The Chen notation identifies a weak entity by using a double-walled entity _____.

optional

Participation is _____ if one entity occurrence does not require a corresponding entity occurrence in a particular relationship.

small circle (O)

In Crow's Foot notation, an optional relationship between entities is shown by drawing a(n) _____ on the side of the optional entity.

participation

Failure to understand the distinction between mandatory and optional _____ in relationships might yield designs in which awkward (and unnecessary) temporary rows must be created.

degree

A relationship _____ indicates the number of entities or participants associated with a relationship.

iterative

A(n) _____ process is based on repetition of processes and procedures.

relationships

Identifying the attributes of entities helps in the better understanding of _____ among entities.

Documentation

_____ not only helps database designers to stay on track during the design process, it also enables them to pick up the design thread when the time comes to modify the design.

high

In organizations that generate large numbers of transactions, _____ processing speeds are often a top priority in database design, which result in minimal access time.