Database Management System
Questions 41 to 50
41.
|
A super
key is any key that uniquely identifies each
(a) Entity uniquely (b)
Object in a table (c) Table
(d) Structure in a table (e)
Column uniquely.
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42.
|
A table
can be logically connected to another table by defining a
(a) Hyperlink (b) Common attribute (c)
Primary key
(d) Candidate key (e) Super Key.
|
43.
|
A primary
key that consists of more than one field is called a
(a) Composite key (b)
Secondary key (c) Group key
(d) All of the above (e) None of the above.
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44.
|
Which of
the following statements concerning the primary key is true?
(a) All primary key entries are unique
(b) The primary key may be null
(c) The primary key is not required for all
tables
(d) The primary key data does not have to be
unique
(e) For every primary key there must be a
foreign key.
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45.
|
In the
context of a database table, the statement "A determines B"
indicates that
(a) Knowing the value of attribute A you can
not look up the value of attribute B
(b) You do not need to know the value of
attribute A in order to look up the value of attribute
(c) Knowing the value of attribute B you can
look up the value of attribute A
(d) Knowing the value of attribute A you can
look up the value of attribute B
(e) None of the above.
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46.
|
A super
key that does not contain a subset of attributes that is itself a super key
is called a
(a) Candidate key (b) Primary key (c) Super key
(d) Secondary key (e) Foreign key.
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47.
|
A table
that displays data redundancies yields ____________ anomalies.
(a) Update (b) Insertion (c) Deletion
(d) All of the above (e)
None of the above.
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48.
|
A table
is in the Fourth Normal Form (4NF) if
(a) All attributes must be dependent on the
primary key, and must be dependent on each other
(b) All attributes must be dependent on the
primary key, but must be independent of each other
(c) No row can contain two or more multivalued
facts about an entity
(d) A and C
(e) B and C.
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49.
|
A table
where all attributes are dependent on the primary key and are independent of
each other, and no row contains two or more multivalued facts about an
entity, is said to be in
(a) 1NF (b) 2NF (c) 3NF (d) 4NF (e) BCNF.
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50.
|
The basic
SQL aggregate function that gives the number of rows containing not null
values for the given column is
(a) MIN (b) COUNT (c) MAX (d) SUM (e) AVG.
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Answers
41.
|
Answer : (a)
Reason : Super key is any key that uniquely identifies
each entity uniquely
|
42.
|
Answer : (b)
Reason : Common attribute is maintained to connect two
tables logically
|
43.
|
Answer : (a)
Reason : A primary key that consists of more
than one field is called Composite key
|
44.
|
Answer : (a)
Reason: All primary keys are unique.
|
45.
|
Answer : (d)
Reason : The answer is evident
|
46.
|
Answer : (a)
Reason: The minimal set of super key is called
candidate key.
|
47.
|
Answer : (d)
Reason : Table that displays data redundancies
yields update, insertion, deletion anomalies
|
48.
|
Answer : (e)
Reason : The answer is evident
|
49.
|
Answer : (d)
Reason : Answer is obvious
|
50.
|
Answer : (b)
Reason : Count function gives the number of rows
containing not null values for the given column
|
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IN Question 42 Answer is C= Primary Key
ReplyDeletesame is answered by you in previous questions