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Database Concepts Study Set 1

Computing

Quiz 4 :

Data Modeling and the Entity Relationship Model

Quiz 4 :

Data Modeling and the Entity Relationship Model

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In a 1:1 relationship,a single entity instance of one type is related to a single entity instance of the same or another type.
Free
True False
Answer:

Answer:

True

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An entity identifier can be either unique or nonunique.
Free
True False
Answer:

Answer:

True

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Subtype entities may be either exclusive or inclusive.
Free
True False
Answer:

Answer:

True

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Recursive relationships can be represented as 1:N or N:M,but not 1:1.
True False
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The E-R Model assumes that all instances of a given entity class have the same attributes.
True False
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The subtype symbol is a circle with a line under it.
True False
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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.
True False
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Recursive relationships occur when an entity has a relationship with ________.
Short Answer
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Which of the following is true about identifiers of entities?
Multiple Choice
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When an entity class has a relationship with itself,it is called a(n)________ relationship.
Short Answer
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There is usually only one instance of an entity in an entity class.
True False
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Unified Modeling Language (UML)has quickly replaced the E-R Model as the most popular technique for creating data models.
True False
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In the Entity-Relationship data model,all instances of an entity of a given type are grouped into ________.
Multiple Choice
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The number of entity classes involved in a relationship is the cardinality of the relationship.
True False
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One or more entities can be associated together in relationships.
True False
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It is possible for an entity to have a relationship to itself.
True False
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Which of the following is not a basic element of the E-R Model?
Multiple Choice
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An entity class is described by the structure of the entities in that class.
True False
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A PRODUCT entity instance is the collection of all PRODUCT entity classes.
True False
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One type of strong entity is the ID-dependent entity.
True False
Answer:
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