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20 Cards in this Set
- Front
- Back
Subtype entities may be either exclusive or inclusive.
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True
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The E-R Model assumes that all instances of a given entity class have the same
attributes. |
True
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If one instance of ENTITY B must be related to one and only one instance of ENTITY
A, and one instance of ENTITY A may be related to many instances of ENTITY B, which of the following should be written in the relationship symbol of the figure below? |
1:N
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If one instance of ENTITY B must be related to one and only one instance of ENTITY
A, and one instance of ENTITY A may be related to many instances of ENTITY B, which of the following should be written in the relationship symbol of the figure below? |
1:N
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In crow's foot E-R notation, a circle indicates a minimum cardinality of zero.
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True
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A dashed line between entities indicates:
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a nonidentifying relationship.
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In crow's foot style E-R diagrams, a crow's foot mark on the relationship line near an
entity indicates: |
a maximum cardinality of many.
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Maximum cardinality indicates whether or not an instance of one entity class must be
related to at least one instance of another entity class. |
False
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The number of entity classes involved in a relationship is known as the relationship's:
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degree
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During the design phase of developing a database system, the users are asked about the
need for changes to existing forms and reports. |
True
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The PRODUCT entity instance is the collection of all PRODUCT entity classes.
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False
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The number of entity classes involved in a relationship is the cardinality of the
relationship. |
False
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It is possible for an entity to have a relationship to itself.
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True
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During the design phase of developing a database system, the data model is
transformed into a database design. |
True
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Use cases can be used to validate the data model, design, and implementation.
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True
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Given only the excerpt of an E-R model shown in the figure below, which of the following is known to be true?
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A single instance of ENTITY B may be related to many
instances of ENTITY A. |
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Which of the following is not a basic element of the E-R Model?
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Use cases
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In crow's foot style E-R diagrams, a single entity together with a related set of entities
that each contain specific sets of attributes related to the single entity represent: |
a supertype / subtype relationship
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An ID-dependent entity is:
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Both a special type of weak entity and an entity in which the
identifier of the entity includes the identifier of another entity |
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Whether or not an instance of one entity class must participate in a relationship with
another entity class is indicated by the: |
minimum cardinality.
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