COSC 61 Review Questions and Answers Graded A+
1) The identifier of the entity becomes the ________ of the corresponding table.
A) primary key
B) foreign key
C) supertype
D) subtype - Answers a
2) The ideal primary key is ________.
A) short
B) numeric
C) fixed
D) A and B
E) A, B, and C -...
1) The identifier of the entity becomes the ________ of the corresponding table.
A) primary key
B) foreign key
C) supertype
D) subtype - Answers a
2) The ideal primary key is ________.
A) short
B) numeric
C) fixed
D) A and B
E) A, B, and C - Answers e
3) A surrogate key should be considered when ________.
A) a relationship is M:N
B) a composite key is required
C) the key contains a lengthy text field
D) the key contains a number
E) an index needs to be created - Answers c
4) Which of the following is not true about surrogate keys?
A) They are identifiers that are supplied by the system, not the users.
B) They have no meaning to the users.
C) They are non-unique within a table.
D) They can be problematic when combining databases.
E) The DBMS will not allow their values to be changed. - Answers c
5) One of the important properties of a column is whether or not it is ________.
, A) found in more than one entity
B) required
C) character or numeric
D) subject to normalization
E) subject to denormalization - Answers b
6) In a relational database design, all relationships are expressed by ________.
A) creating a primary key
B) creating a foreign key
C) creating a supertype
D) creating a subtype
E) creating a line between entities - Answers b
7) Which of the following would be a reason to denormalize a relation?
A) Relax security
B) Lack of design time
C) End user preference
D) Improve performance
E) None of the above - Answers d
8) Which of the following is true about representing a weak entity with the relational model?
A) If the weak entity is existence-dependent, the key of the parent must be part of the key of the weak
entity.
B) If the strong entity has a minimum cardinality of 1, the key of the weak entity must be part of the
strong entity.
C) If the weak entity is ID-dependent, the key of the weak entity must be part of the key of the parent
entity.
D) If the weak entity is ID-dependent, the key of the parent entity must be part of the key of the weak
entity.
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