ER Model and Business Rules
Q. In an ER model, how is a one-to-many relationship typically represented?
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A.
With a single line connecting two entities
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B.
With a crow's foot notation
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C.
With a dashed line
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D.
With a double line
Solution
A one-to-many relationship is typically represented with a crow's foot notation.
Correct Answer: B — With a crow's foot notation
Q. What does the term 'cardinality' refer to in an ER model?
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A.
The number of attributes in an entity
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B.
The number of entities in a relationship
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C.
The type of data stored in an entity
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D.
The uniqueness of an entity
Solution
Cardinality refers to the number of entities involved in a relationship.
Correct Answer: B — The number of entities in a relationship
Q. What is a weak entity in an ER model?
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A.
An entity that cannot exist without a strong entity
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B.
An entity with no attributes
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C.
An entity that has a composite key
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D.
An entity that is not related to any other entity
Solution
A weak entity is one that cannot exist without a strong entity.
Correct Answer: A — An entity that cannot exist without a strong entity
Q. What is the primary key in an entity?
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A.
A unique identifier for each record
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B.
An attribute that can be null
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C.
A foreign key from another entity
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D.
An attribute that is not used in relationships
Solution
The primary key is a unique identifier for each record in an entity.
Correct Answer: A — A unique identifier for each record
Q. Which of the following best describes a business rule?
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A.
A guideline for database design
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B.
A constraint on data values
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C.
A policy that governs data usage
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D.
All of the above
Solution
A business rule can be a guideline, a constraint, or a policy regarding data.
Correct Answer: D — All of the above
Q. Which of the following is an example of an attribute in an ER model?
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A.
Customer
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B.
Orders
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C.
OrderID
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D.
Many-to-Many
Solution
OrderID is an example of an attribute in an ER model.
Correct Answer: C — OrderID
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