Engineering Questions with Answers - Multiple Choice Questions

MCQs on Set Operations

1 - Question

The union operation is represented by
a) ∩
b) U
c) –
d) *

View Answer

Answer: b
Explanation: Union operator combines the relations.




2 - Question

The intersection operator is used to get the _____ tuples.
a) Different
b) Common
c) All
d) Repeating

View Answer

Answer: b
Explanation: Intersection operator ignores unique tuples and takes only common ones.




3 - Question

The union operation automatically __________ unlike the select clause.
a) Adds tuples
b) Eliminates unique tuples
c) Adds common tuples
d) Eliminates duplicate

View Answer

Answer: d
Explanation: None.




4 - Question

If we want to retain all duplicates, we must write ________ in place of union.
a) Union all
b) Union some
c) Intersect all
d) Intersect some

View Answer

Answer: a
Explanation: Union all will combine all the tuples including duplicates.




5 - Question

(SELECT course id
FROM SECTION
WHERE semester = ’Fall’ AND YEAR= 2009)
EXCEPT
(SELECT course id
FROM SECTION
WHERE semester = ’Spring’ AND YEAR= 2010);

This query displays
a) Only tuples from second part
b) Only tuples from the first part which has the tuples from second part
c) Tuples from both the parts
d) Tuples from first part which do not have second part

View Answer

Answer: d
Explanation: Except keyword is used to ignore the values.




6 - Question

For like predicate which of the following is true.

i) % matches zero OF more characters.
ii) _ matches exactly one CHARACTER.

a) i-only
b) ii-only
c) i & ii
d) None of the mentioned

View Answer
Answer: a
Explanation:% is used with like and _ is used to fill in the character.

 




7 - Question

The number of attributes in relation is called as its
a) Cardinality
b) Degree
c) Tuples
d) Entity

View Answer

Answer: b
Explanation: None.




8 - Question

_____ clause is an additional filter that is applied to the result.
a) Select
b) Group-by
c) Having
d) Order by

View Answer
Answer: c
Explanation: Having is used to provide additional aggregate filtration to the query.

 




9 - Question

_________ joins are SQL server default
a) Outer
b) Inner
c) Equi
d) None of the mentioned

View Answer

Answer: b
Explanation: It is optional to give the inner keyword with the join as it is default.




10 - Question

The _____________ is essentially used to search for patterns in target string.
a) Like Predicate
b) Null Predicate
c) In Predicate
d) Out Predicate

View Answer

Answer: a
Explanation: Like predicate matches the string in the given pattern.

Get weekly updates about new MCQs and other posts by joining 18000+ community of active learners