DBMS Multiple choice Questions and Answers-Relational Databases

51.	When mapping a ternary relationship with an associative entity into a relation which of the following is true?
a.	One relation is created.
b.	Two relations are created.
c.	Three relations are created.
d.	Four relations are created.

Answer: (d).Four relations are created.

52.	When mapping a supertype/subtype relationship which of the following is true?
a.	The supertype primary key is assigned to each subtype.
b.	The subtype primary key is assigned to each supertype.
c.	There is no link between the supertype/subtype entities.
d.	There is no primary key/foreign key relationship between a supertype/subtype.

Answer: (a).The supertype primary key is assigned to each subtype.

53.	If no multivalued attributes exist in a relation, then the relation is in what normal form?
a.	First normal form
b.	Second normal form
c.	Third normal form
d.	Fourth normal form

Answer: (a).First normal form

54.	If no multivalued attributes exist and no partial dependencies exist in a relation, then the relation is in what normal form?
a.	First normal form
b.	Second normal form
c.	Third normal form
d.	Fourth normal form

Answer: (b).Second normal form

55.	A transitive dependency is which of the following?
a.	A functional dependency between two or more key attributes.
b.	A functional dependency between two or more nonkey attributes.
c.	A relation that is in first normal form.
d.	A relation that is in second normal form.

Answer: (b).A functional dependency between two or more nonkey attributes.

56.	What is the best data type definition for Oracle when a field is alphanumeric and has a fixed length?
a.	VARCHAR2
b.	CHAR
c.	LONG
d.	NUMBER

Answer: (b).CHAR

57.	If a denormalization situation exists with a many-to-many or associative binary relationship, which of the following is true?
a.	All fields are stored in one relation.
b.	All fields are stored in two relations.
c.	All fields are stored in three relations.
d.	All fields are stored in four relations.

Answer: (b).All fields are stored in two relations.

58.	Which of the following is an advantage of partitioning?
a.	Complexity
b.	Inconsistent access speed
c.	Extra space
d.	Security

Answer: (d).Security

59.	Sequential retrieval on a primary key for sequential file storage has which of the following features?
a.	Very fast
b.	Moderately fast
c.	Slow
d.	Impractical

Answer: (a).Very fast

60.	A rule of thumb for choosing indexes for a relational database includes which of the following?
a.	Indexes are more useful on smaller tables.
b.	Indexes are more useful for columns that do not appear frequently in the WHERE clause in queries.
c.	Do not specify a unique index for the primary key of each table.
d.	Be careful indexing attributes that have null values.

Answer: (d).Be careful indexing attributes that have null values.