Question : Why is “Address” usually not preferred as a primary key?
Solution :
Correct Answer : It can change frequently
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Question : Which key is NOT necessarily minimal?
Solution :
Correct Answer : Super Key
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Question : Which of the following best describes a super key?
Solution :
Correct Answer : Set of attributes that uniquely identify a tuple
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Question : If a table has multiple candidate keys, then:
Solution :
Correct Answer : Only one can be selected as primary key
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Question : A composite key is:
Solution :
Correct Answer : A key formed using multiple attributes
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Question : Which key is used to maintain referential integrity between tables?
Solution :
Correct Answer : Foreign Key
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Question : If a relation has 5 attributes, the maximum number of possible super keys is:
Solution :
Correct Answer : 31
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Question : Which of the following can contain NULL values?
Solution :
Correct Answer : Foreign Key
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Question : Which statement is FALSE regarding keys?
Solution :
Correct Answer : All super keys are candidate keys
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Question : A super key from which no attribute can be removed without losing uniqueness is called:
Solution :
Correct Answer : Candidate Key
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Question : In a relationship, if both participating entity sets can have multiple associations with each other, which constraint applies?
Solution :
Correct Answer : M:M
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Question : The structure of the primary key of a relationship set in ER modeling depends primarily on:
Solution :
Correct Answer : Mapping cardinalities
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Question : Which of the following statements is TRUE regarding mapping cardinalities?
Solution :
Correct Answer : They are also known as cardinality ratios
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Question : Consider two entity sets A and B with a relationship R. If each entity in A can be associated with multiple entities in B, but each entity in B is associated with at most one entity in A, the mapping is:
Solution :
Correct Answer : 1:M
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Question : Which of the following best defines a mapping constraint in DBMS?
Solution :
Correct Answer : It defines how many entities can be associated via a relationship
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Question : Which of the following is NOT a type of attribute in an ER model?
Solution :
Correct Answer : Functional
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Question : Which statement best defines cardinality in an ER model?
Solution :
Correct Answer : Number of entity instances related to another entity instance
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Question : What is the degree of a relationship if three entities participate in it?
Solution :
Correct Answer : Ternary
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Question : In an ER diagram, a derived attribute is represented by:
Solution :
Correct Answer : Dashed ellipse
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Question : Which of the following correctly describes a weak entity in an ER model?
Solution :
Correct Answer : It depends on another entity and has no primary key
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