Chapter 4: Entity Relationship (ER) Modeling – Flashcards

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The ____ is independent of the database type.
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ERM
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____ models are used in the conceptual design of databases.
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Conceptual
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Relation models are used in the ____ design of databases.
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logical
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The ERM (Entity Relationship Model) forms the bases of an ____.
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ERD (Entity Relationship Diagram)
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The ____ represents the conceptual database as viewed by the end user,
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ERD (Entity Relationship Diagram)
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A ____ depicts the database's main components: entities, attributes and relationships.
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ERD (Entity Relationship Diagram)
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The word entity and ____ are often used interchangeably.
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object
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The ____ notation favors conceptual modeling.
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Chen
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The ____ notation favors a more implementation-oriented approach.
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Crow's foot
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The ____ notation can be used for both conceptual and implementation modeling.
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UML
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An ____ in the ERM corresponds to a table-not a row- in the relational environment.
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entity
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The ERM refers to a table row an an ____ or the entity's name.
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entity occurance
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A ____ attribute is an attribute that must have a value; therefore, it cannot be left empty.
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required
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An ____ attribute is an attribute that does not require a value; therefore, it can be left empty.
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optional
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True or False: Attributes do not have a domain.
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False
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A ____ is a set of possible values given to an attribute.
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domain
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True of False: Attributes may share a domain.
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True
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True or False:The data dictionary may let a newly declared attribute inherit the characteristics of an existing attribute of the same attribute name is used.
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True, PROFESSOR and STUDENT entities may each have an attribute named address.
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An ____ , one or more attributes that uniquely identify each entity instance.
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identifier (primary key)
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In the ERD, ____ are underlined.
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identifiers (primary key)
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A ____ identifier is a primary key composed of more than one attribute.
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composite
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If a ____ key was deleted, the ____ key would become an acceptable composite primary key because the instance would still be uniquely identifiable.
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primary, candidate
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True or False: Attributes are classified as simple or composite?
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True
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A ____ attribute is an attribute that can be further subdivided to yield additional attributes.
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composite
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A ____ attribute is an attribute that cannot be subdivided.
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simple
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A ____ attribute is an attribute that can have only a single value.
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single-valued
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True or False: A single-valued attribute is always a simple attribute.
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False
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A ____ attribute are attributes that can have many values.
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multivalued
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True or False: If possible, it is best to create a new entity set composed of multivalued attribute components rather than to make multivalued attributes into their own attribute.
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True
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A ____ attribute is an attribute whose value is calculated (derived) from other attributes.
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derived
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The ____ notation does not have a method for distinguishing the derived attribute from other attributes.
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Crow's foot
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Derived attributes are sometimes referred to as ____ attributes.
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computed
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The entities that participate in relationships are also knows as ____.
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participants
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Each relationship name (describes the relationship) is an ____ or ____ verb.
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active or passive
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The term ____ is used to describe the relationship classification.
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connectivity
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____ expresses the minimum and maximum number of entity occurrences associated with one occurrence of the related entity.
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Cadinality
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The DBMS cannot implement ____ at the table level-that capability is provided by the application software or by triggers.
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cardinalities
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Connectivities and cardinalities are established by concise statements known as ____.
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business rules
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An entity is said to be ____ if it can exist in the database only when it is associated with another related entity occurrence.
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existence-dependent
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An entity is ____ if it has a mandatory foreign key-that is, a foreign key attribute that cannot be null.
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existence-dependent
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If an entity can exist apart from all of its related entities, then it is ____.
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existence-independent
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An existence-dependent entity is also referred to as a ____ or ____.
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strong entity, regular entity
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The concept of ____ strength is based on how the primary key of a related entity is defined.
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relationship
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True or False: The DBMS cannot handle the implementation of the cardinalities at the table level?
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True
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Connectivities and ____ are established by concise statements known as business rules?
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cardinalities
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True or False: The relationship strength is part of the original ERM?
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False, it only directly applies to Crow's Foot diagrams
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It is important to understand ____ strength as it affects database implementation.
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relationship
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A ____ or ____, exists if the primary key of the related entity does not contain a primary key component of the parent entity.
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weak relationship or non-identifying relationship
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A ____ or ____, exists when the primary key of the related entity contains a primary component of the parent entity.
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Strong relationship or identifying relationship
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True of False: The order in which the tables are created and loaded is very important.
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True
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You must load the data of the ____ side first in a 1:M relationship to avoid the possibility o referential integrity errors, regardless of whether the relationships are weak or strong.
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1
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A weak entity must meet two conditions:
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1. The entity is existence-dependent: it cannot exist without the entity with which it has a relationship 2. The entity has a primary key that is partially or totally derived from the parent entity in the relationship
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The database designed usually determines whether an entity can be described as weak based on the ____.
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business rules
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Participation in a relationship is either ____ or ____.
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optional or mandatory
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You must consider the bidirectional nature of the relationship when determining ____.
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participation
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____ participation means that one entity occurrence does not require a corresponding entity occurrence in a particular relationship.
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Optional
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The existence of an ____ entity indicatives that its minimum cardinality is 0.
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optional
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The term ____ is used to label any condition in which one or more optional relationships exist.
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optionality
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The burden of establishing the relationship is always placed on the ____ that contains the foreign key.
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entity (the "many" side of the relationship)
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____ participation means that one entity occurrence requires a corresponding entity occurrence is a particular relationship.
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Mandatory
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If no optionality symbol is depicted with the entity, the entity is assumed to exist in a ____ relationship with the related entity
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mandatory
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The existence of a mandatory relationship indicates that the minimum cardinality is a least ____ for the mandatory entity.
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1
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True or False: Relationship strength and relationship participation mean the same thing.
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False
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A ____ relationship can exist when one entity is optional to another.
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strong
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It is possible for a ____ relationship to be established when one entity is mandatory to another.
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weak
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The relationship ____ depends on how the PK of the related entity is formulated, while the relationship ____ depends on how the business rule is written
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strength, participation
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A ____ indicates the number of entities or participants associated with a relationship.
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relationship degree
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A ____ relationship exists when an association is maintained within a single entity.
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unary
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A ____ relationship exists when two entities are associated.
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binary
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A ____ relationship exists when three entities are associated.
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ternary
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True or False: One common pitfall when working with unary relationships is to confuse participation with referential integrity.
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True
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True or False: Participation is bidirectional and it must be addressed in both directions along the relationship
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True
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True or False: Referential integrity is not bidirectional.
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True
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Both ____ and ____ involve the values used as PKs and FKs to implement the relationship
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participation and referential integrity
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____ requires that the values in the FK correspond to values in the PK.
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Referential integrity
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A ____ relationship is one in which a relationship can exist between occurrences of the same entity set.
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recursive
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A ____ entity, is a 1:M relationship with the parent entities and is composed of the PK attributes of each parent entity.
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composite entity, bridge or associative entity
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When using the Crow's foot notation, the associative entity is identified as a strong (identifying) relationship, as indicated by the _____ relationship line between the parents and associative entity.
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solid
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An ____ is based on repetition of processes and procedures.
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iterative process
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True or False: The ERD process is repeated until the end users and designers agree that the ERD is a fair representation of the organization's activities and functions.
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True
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Cardinality (N) means?
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indeterminate
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True or False: Do not use 1:1 relationships lightly and make sure that the relationship within the database design is defensible.
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True
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True or False: Database designers must often make design compromises that are triggered by conflicting goals, such as adherence to design standards (design elegance), processing speed and information requirements.
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True
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____ standards guide you in developing logical structures that minimize data redundancies, thereby minimizing the likelihood of destructive data anomalies.
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Design
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Without ____, it is nearly impossible to formulate a proper design process, to evaluate an existing design, or to trace the likely logical impact of changes in design.
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design standards
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____ speeds means minimal access time, which may be achieved by minimizing the number and complexity of logically desired relationships.
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Processing
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A database may have to sacrifice some of its "clean design structures and high transaction speed to ensure maximum ____.
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information generation
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True or False:While focusing on entities, attributes, relationships and constraint, the designer should begin thinking about end-user requirements such as performance, security, shared access and data integrity.
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True
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