A directory of Objective Type Questions covering all the Computer Science subjects. Here you can access and discuss Multiple choice questions and answers for various compitative exams and interviews.

221. In SQL, .................. is an Aggregate function.
a. SELECT
b. CREATE
c. AVG
d. MODIFY
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Answer: (c).AVG

222. Match the following with respect to RDBMS:

List - I
(a) Entity integrity
(b) Domain integrity
(c) Referential integrity
(d) Userdefined integrity

List - II
(i) enforces some specific business rule that do not fall into entity or domain
(ii) Rows can't be deleted which are used by other records
(iii) enforces valid entries for a column
(iv) No duplicate rows in a table

Code:
(a) (b) (c) (d)
a. (iii) (iv) (i) (ii)
b. (iv) (iii) (ii) (i)
c. (iv) (ii) (iii) (i)
d. (ii) (iii) (iv) (i)
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Answer: (b).(iv) (iii) (ii) (i)

223. In RDBMS, different classes of relations are created using ................... technique to prevent modification anomalies.
a. Functional Dependencies
b. Data integrity
c. Referential integrity
d. Normal Forms
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Answer: (d).Normal Forms

224. .................. SQL command changes one or more fields in a record.
a. LOOK-UP
b. INSERT
c. MODIFY
d. CHANGE
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Answer: (c).MODIFY

225. If every non-key attribute is functionally dependent on the primary key, then the relation is in ....................
a. First normal form
b. Second normal form
c. Third normal form
d. Fourth normal form
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Answer: (c).Third normal form

226. Consider a relation R (A, B, C, D, E, F, G, H), where each attribute is atomic, and following functional dependencies exist.

CH → G
A → BC
B → CFH
E → A
F → EG

The relation R is ....................
a. in 1NF but not in 2NF
b. in 2NF but not in 3NF
c. in 3NF but not in BCNF
d. in BCNF
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Answer: (a).in 1NF but not in 2NF

227. Given two relations R1(A, B) and R2(C, D), the result of following query
Select distinct A, B from R1, R2
is guaranteed to be same as R1 provided one of the following condition is satisfied.
a. R1 has no duplicates and R2 is empty.
b. R1 has no duplicates and R2 is non - empty.
c. Both R1 and R2 have no duplicates.
d. R2 has no duplicates and R1 is non - empty.
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Answer: (b).R1 has no duplicates and R2 is non - empty.

228. Consider a schema R(A, B, C, D) and following functional dependencies.

A → B
B → C
C → D
D → B

Then decomposition of R into R1(A, B), R2(B, C) and R3(B, D) is ..................
a. Dependency preserving and lossless join.
b. Lossless join but not dependency preserving.
c. Dependency preserving but not lossless join.
d. Not dependency preserving and not lossless join.
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Answer: (a).Dependency preserving and lossless join.