Computer Science Engineering (CSE) Exam > Computer Science Engineering (CSE) Questions > Given relations R(w, x) and S(y, z), the resu...
Start Learning for Free
Given relations R(w, x) and S(y, z), the result of
SELECT DISTINCT w,x
FROM R, S
Is guaranteed to be same as R, if
SELECT DISTINCT w,x
FROM R, S
Is guaranteed to be same as R, if
- a)R has no duplicates and S is non-empty
- b)R and S have no duplicates
- c)S has no duplicates and R is non-empty
- d)R and S have the same number of tuples
Correct answer is option 'A'. Can you explain this answer?
Verified Answer
Given relations R(w, x) and S(y, z), the result ofSELECT DISTINCT w,xF...
The given query
SELECT DISTINCT W, X
FROM R, S
Is guaranteed to be same as R, if R has no duplicates and ‘S’ is non-empty.
Since, if R is having a duplicates, then the tuples selected by SELECT operation of the R and the given query will not be same also if ‘S’ is empty then the given query outputs null.
SELECT DISTINCT W, X
FROM R, S
Is guaranteed to be same as R, if R has no duplicates and ‘S’ is non-empty.
Since, if R is having a duplicates, then the tuples selected by SELECT operation of the R and the given query will not be same also if ‘S’ is empty then the given query outputs null.
Most Upvoted Answer
Given relations R(w, x) and S(y, z), the result ofSELECT DISTINCT w,xF...
Explanation:
To understand why option 'A' is the correct answer, let's analyze each option and its implications on the result of the query.
a) R has no duplicates and S is non-empty:
- If R has no duplicates, then each tuple in R is unique based on the attributes w and x.
- If S is non-empty, it means it has at least one tuple.
- When we perform a Cartesian product of R and S (by not specifying any join condition), each tuple in R will be combined with each tuple in S.
- Since R has no duplicates and S is non-empty, the result of the Cartesian product will have distinct tuples, and therefore the SELECT DISTINCT clause will have no effect. The result will be the same as R.
b) R and S have no duplicates:
- If R and S have no duplicates, it means that each tuple in both R and S is unique based on their respective attributes.
- When we perform a Cartesian product of R and S, the result will have unique tuples as well.
- However, the SELECT DISTINCT clause will still be applied, and it will eliminate any duplicate tuples that may have been introduced by other operations in the query.
- Therefore, the result may not be the same as R.
c) S has no duplicates and R is non-empty:
- If S has no duplicates, then each tuple in S is unique based on the attributes y and z.
- If R is non-empty, it means it has at least one tuple.
- When we perform a Cartesian product of R and S, the result will have combinations of tuples from both relations.
- Since S has no duplicates and R is non-empty, the result may contain duplicate tuples, as each tuple in R is combined with each tuple in S.
- The SELECT DISTINCT clause will eliminate any duplicate tuples in the result, but it will not guarantee that the result will be the same as R.
d) R and S have the same number of tuples:
- If R and S have the same number of tuples, it means they have the same cardinality.
- When we perform a Cartesian product of R and S, the result will have a cardinality equal to the product of the cardinalities of R and S.
- The SELECT DISTINCT clause will eliminate any duplicate tuples in the result, but it will not guarantee that the result will be the same as R, as the tuples themselves may be different.
Therefore, the only option that guarantees the result of SELECT DISTINCT w, x FROM R, S to be the same as R is option 'A', where R has no duplicates and S is non-empty.
To understand why option 'A' is the correct answer, let's analyze each option and its implications on the result of the query.
a) R has no duplicates and S is non-empty:
- If R has no duplicates, then each tuple in R is unique based on the attributes w and x.
- If S is non-empty, it means it has at least one tuple.
- When we perform a Cartesian product of R and S (by not specifying any join condition), each tuple in R will be combined with each tuple in S.
- Since R has no duplicates and S is non-empty, the result of the Cartesian product will have distinct tuples, and therefore the SELECT DISTINCT clause will have no effect. The result will be the same as R.
b) R and S have no duplicates:
- If R and S have no duplicates, it means that each tuple in both R and S is unique based on their respective attributes.
- When we perform a Cartesian product of R and S, the result will have unique tuples as well.
- However, the SELECT DISTINCT clause will still be applied, and it will eliminate any duplicate tuples that may have been introduced by other operations in the query.
- Therefore, the result may not be the same as R.
c) S has no duplicates and R is non-empty:
- If S has no duplicates, then each tuple in S is unique based on the attributes y and z.
- If R is non-empty, it means it has at least one tuple.
- When we perform a Cartesian product of R and S, the result will have combinations of tuples from both relations.
- Since S has no duplicates and R is non-empty, the result may contain duplicate tuples, as each tuple in R is combined with each tuple in S.
- The SELECT DISTINCT clause will eliminate any duplicate tuples in the result, but it will not guarantee that the result will be the same as R.
d) R and S have the same number of tuples:
- If R and S have the same number of tuples, it means they have the same cardinality.
- When we perform a Cartesian product of R and S, the result will have a cardinality equal to the product of the cardinalities of R and S.
- The SELECT DISTINCT clause will eliminate any duplicate tuples in the result, but it will not guarantee that the result will be the same as R, as the tuples themselves may be different.
Therefore, the only option that guarantees the result of SELECT DISTINCT w, x FROM R, S to be the same as R is option 'A', where R has no duplicates and S is non-empty.
|
Explore Courses for Computer Science Engineering (CSE) exam
|
|
Top Courses for Computer Science Engineering (CSE)View all
Question Description
Given relations R(w, x) and S(y, z), the result ofSELECT DISTINCT w,xFROM R, SIs guaranteed to be same as R, ifa)R has no duplicates and S is non-emptyb)R and S have no duplicatesc)S has no duplicates and R is non-emptyd)R and S have the same number of tuplesCorrect answer is option 'A'. Can you explain this answer? for Computer Science Engineering (CSE) 2025 is part of Computer Science Engineering (CSE) preparation. The Question and answers have been prepared according to the Computer Science Engineering (CSE) exam syllabus. Information about Given relations R(w, x) and S(y, z), the result ofSELECT DISTINCT w,xFROM R, SIs guaranteed to be same as R, ifa)R has no duplicates and S is non-emptyb)R and S have no duplicatesc)S has no duplicates and R is non-emptyd)R and S have the same number of tuplesCorrect answer is option 'A'. Can you explain this answer? covers all topics & solutions for Computer Science Engineering (CSE) 2025 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Given relations R(w, x) and S(y, z), the result ofSELECT DISTINCT w,xFROM R, SIs guaranteed to be same as R, ifa)R has no duplicates and S is non-emptyb)R and S have no duplicatesc)S has no duplicates and R is non-emptyd)R and S have the same number of tuplesCorrect answer is option 'A'. Can you explain this answer?.
Given relations R(w, x) and S(y, z), the result ofSELECT DISTINCT w,xFROM R, SIs guaranteed to be same as R, ifa)R has no duplicates and S is non-emptyb)R and S have no duplicatesc)S has no duplicates and R is non-emptyd)R and S have the same number of tuplesCorrect answer is option 'A'. Can you explain this answer? for Computer Science Engineering (CSE) 2025 is part of Computer Science Engineering (CSE) preparation. The Question and answers have been prepared according to the Computer Science Engineering (CSE) exam syllabus. Information about Given relations R(w, x) and S(y, z), the result ofSELECT DISTINCT w,xFROM R, SIs guaranteed to be same as R, ifa)R has no duplicates and S is non-emptyb)R and S have no duplicatesc)S has no duplicates and R is non-emptyd)R and S have the same number of tuplesCorrect answer is option 'A'. Can you explain this answer? covers all topics & solutions for Computer Science Engineering (CSE) 2025 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Given relations R(w, x) and S(y, z), the result ofSELECT DISTINCT w,xFROM R, SIs guaranteed to be same as R, ifa)R has no duplicates and S is non-emptyb)R and S have no duplicatesc)S has no duplicates and R is non-emptyd)R and S have the same number of tuplesCorrect answer is option 'A'. Can you explain this answer?.
Solutions for Given relations R(w, x) and S(y, z), the result ofSELECT DISTINCT w,xFROM R, SIs guaranteed to be same as R, ifa)R has no duplicates and S is non-emptyb)R and S have no duplicatesc)S has no duplicates and R is non-emptyd)R and S have the same number of tuplesCorrect answer is option 'A'. Can you explain this answer? in English & in Hindi are available as part of our courses for Computer Science Engineering (CSE).
Download more important topics, notes, lectures and mock test series for Computer Science Engineering (CSE) Exam by signing up for free.
Here you can find the meaning of Given relations R(w, x) and S(y, z), the result ofSELECT DISTINCT w,xFROM R, SIs guaranteed to be same as R, ifa)R has no duplicates and S is non-emptyb)R and S have no duplicatesc)S has no duplicates and R is non-emptyd)R and S have the same number of tuplesCorrect answer is option 'A'. Can you explain this answer? defined & explained in the simplest way possible. Besides giving the explanation of
Given relations R(w, x) and S(y, z), the result ofSELECT DISTINCT w,xFROM R, SIs guaranteed to be same as R, ifa)R has no duplicates and S is non-emptyb)R and S have no duplicatesc)S has no duplicates and R is non-emptyd)R and S have the same number of tuplesCorrect answer is option 'A'. Can you explain this answer?, a detailed solution for Given relations R(w, x) and S(y, z), the result ofSELECT DISTINCT w,xFROM R, SIs guaranteed to be same as R, ifa)R has no duplicates and S is non-emptyb)R and S have no duplicatesc)S has no duplicates and R is non-emptyd)R and S have the same number of tuplesCorrect answer is option 'A'. Can you explain this answer? has been provided alongside types of Given relations R(w, x) and S(y, z), the result ofSELECT DISTINCT w,xFROM R, SIs guaranteed to be same as R, ifa)R has no duplicates and S is non-emptyb)R and S have no duplicatesc)S has no duplicates and R is non-emptyd)R and S have the same number of tuplesCorrect answer is option 'A'. Can you explain this answer? theory, EduRev gives you an
ample number of questions to practice Given relations R(w, x) and S(y, z), the result ofSELECT DISTINCT w,xFROM R, SIs guaranteed to be same as R, ifa)R has no duplicates and S is non-emptyb)R and S have no duplicatesc)S has no duplicates and R is non-emptyd)R and S have the same number of tuplesCorrect answer is option 'A'. Can you explain this answer? tests, examples and also practice Computer Science Engineering (CSE) tests.
|
|
Explore Courses for Computer Science Engineering (CSE) exam
|
|
Signup for Free!
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
|
© EduRev
|
Education Revolution
|
|
Signup to see your scores
go up
within 7 days!
within 7 days!
Takes less than 10 seconds to signup