DBI202 (Full) 3-Practice Questions with
Elaborated Answers.
c - Answer What is a view?
a. A view is a database diagram
b. A view is a special stored procedure executed when certain event occurs
c. A view is a virtual table which results of executing a pre-compiled query. A view is not a part
of the physical database schema, while the regular tables are.
d. None of the others
a - Answer What structure can you implement for the database to speed up table reads?
a. indexes
b. triggers
c. store-procedures
d. synonyms
a - Answer Often, a DBMS allows us to build a single index on ____ attribute(s)
(choose the most correct answer)
a. only one
b. two
c. three
d. multiple
c - Answer Suppose an updatable view ParamountMovies is associated with Movies relation.
Choose a correct answer.
a. Drop Movies relation also delete the view ParamountMovies
b. Drop ParamountMovies also delete Movies
c. An update on ParamountMovies is translated into Movies
d. None of the others
e - Answer Why we should use stored procedures?
a. They allow faster execution
b. They can reduce network traffic
c. They allow modular programming
d. They can be used as a security mechanism
,e. All of the others
a - Answer In UML, a _____ between classes is called an association
a.binary relationship
b.multi-way relationship
c.none of the others
b - Answer When an entity is called "weak"?
(a) When it is used to represent weak objects, such as patients, elders
(b) When all of its attributes can not identify itself
(c) When It always needs support from other entity
(d) When It is not really necessary in the ERD
a.(a) and (b) are correct
b.(b) and (c) are correct
c.(c) and (d) are correct
d.(d) and (a) are correct
b - Answer Consider the following statement:
"When drawing ERD, if an entity has no non-key attribute and it is the 'one' in many-one
relationship, then we should set it to the attribute of other entities"
That above statement describes which principle?
A.Avoid Redundancy Principle
B.Picking the right kind of element principle
C.Limit the use of weak entity sets principle
D.Faithfulness principle
b - Answer When drawing an ERD:
(a)Entity sets and their attributes should reflect reality
(b)Redundancy is not important, so we can ignore it
(c) Avoid introducing more elements into the design than is absolutely necessary
(d) Choosing the right relationships
A.(a) and (b) and (c) are correct
B.(a) and (c) and (d) are correct
, C.(a) and (b) and (d) are correct
D.(b) and (c) and (d) are correct
b - Answer A weak entity
A.does not depend on other entities
B.does not have enough key attribute(s)
C.is an entity that has not any key-attribute
D.None of the others
b - Answer Here are three relations, R(A,B), S(C,D), and T(E,F). Their current values are:
R
AB
-------------------
01
10
11
S
CD
-------------------
01
10
11
T
EF
-------------------
01
10
11
Compute the result of the query:
SELECT A, F, SUM(C), SUM(D)
Elaborated Answers.
c - Answer What is a view?
a. A view is a database diagram
b. A view is a special stored procedure executed when certain event occurs
c. A view is a virtual table which results of executing a pre-compiled query. A view is not a part
of the physical database schema, while the regular tables are.
d. None of the others
a - Answer What structure can you implement for the database to speed up table reads?
a. indexes
b. triggers
c. store-procedures
d. synonyms
a - Answer Often, a DBMS allows us to build a single index on ____ attribute(s)
(choose the most correct answer)
a. only one
b. two
c. three
d. multiple
c - Answer Suppose an updatable view ParamountMovies is associated with Movies relation.
Choose a correct answer.
a. Drop Movies relation also delete the view ParamountMovies
b. Drop ParamountMovies also delete Movies
c. An update on ParamountMovies is translated into Movies
d. None of the others
e - Answer Why we should use stored procedures?
a. They allow faster execution
b. They can reduce network traffic
c. They allow modular programming
d. They can be used as a security mechanism
,e. All of the others
a - Answer In UML, a _____ between classes is called an association
a.binary relationship
b.multi-way relationship
c.none of the others
b - Answer When an entity is called "weak"?
(a) When it is used to represent weak objects, such as patients, elders
(b) When all of its attributes can not identify itself
(c) When It always needs support from other entity
(d) When It is not really necessary in the ERD
a.(a) and (b) are correct
b.(b) and (c) are correct
c.(c) and (d) are correct
d.(d) and (a) are correct
b - Answer Consider the following statement:
"When drawing ERD, if an entity has no non-key attribute and it is the 'one' in many-one
relationship, then we should set it to the attribute of other entities"
That above statement describes which principle?
A.Avoid Redundancy Principle
B.Picking the right kind of element principle
C.Limit the use of weak entity sets principle
D.Faithfulness principle
b - Answer When drawing an ERD:
(a)Entity sets and their attributes should reflect reality
(b)Redundancy is not important, so we can ignore it
(c) Avoid introducing more elements into the design than is absolutely necessary
(d) Choosing the right relationships
A.(a) and (b) and (c) are correct
B.(a) and (c) and (d) are correct
, C.(a) and (b) and (d) are correct
D.(b) and (c) and (d) are correct
b - Answer A weak entity
A.does not depend on other entities
B.does not have enough key attribute(s)
C.is an entity that has not any key-attribute
D.None of the others
b - Answer Here are three relations, R(A,B), S(C,D), and T(E,F). Their current values are:
R
AB
-------------------
01
10
11
S
CD
-------------------
01
10
11
T
EF
-------------------
01
10
11
Compute the result of the query:
SELECT A, F, SUM(C), SUM(D)
