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SQL allows tuples in relations, and correspondingly defines the multiplicity of tuples in the result of joins. Which one of the following queries always gives the same answer as the nested query shown below:
select * from R where a in (select S.a from S)
- a)select R.* from R, S where R.a=S.a (D)
- b)select distinct R.* from R,S where R.a=S.a
- c)select R.* from R,(select distinct a from S) as S1 where R.a=S1.a
- d)select R.* from R,S where R.a=S.a and is unique R
Correct answer is option 'C'. Can you explain this answer?
Verified Answer
SQL allows tuples in relations, and correspondingly defines the multip...
The solution of this question lies in the data set(tuples) of Relations R and S we define. If we miss some case then we may get wrong answer. Let's say, Relation R(BCA) with attributes B, C and A contains the following tuples.
And Relation S(AMN) with attributes A, M, and N contains the following tuples.
Now ,the original Query will give result as: "select * from R where a in (select S.a from S) " - The query asks to display every tuple of Relation R where R.a is present in the complete set S.a.
Option A query will result in : "select R.* from R, S where R.a=S.a"
Option B query will result in : " select distinct R.* from R,S where R.a=S.a"
----------------------------------------------------------------------------------------------------------- Option C query will result in : "select R.* from R,(select distinct a from S) as S1 where R.a=S1.a" B C A --------- 7 2 1 7 2 1 8 9 5 8 9 5 ----------------------------------------------------------------------------------------------------------- Option D query will result in : NULL set "select R.* from R,S where R.a=S.a and is unique R" ---------------------------------------------------------------------------------------------------------- Hence option C query matches the original result set. Note : As mentioned earlier, we should take those data sets which can show us the difference in different queries. Suppose in R if you don't put identical tuples then you will get wrong answers. (Try this yourself, this is left as an exercise for you).
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SQL allows tuples in relations, and correspondingly defines the multip...
Explanation:
The nested query in the question selects all the tuples from relation R where the value of attribute 'a' is present in the set of values obtained by projecting attribute 'a' from relation S. The same result can be obtained using the following query options:
A. SELECT R.* FROM R, S WHERE R.a=S.a:
This option performs a natural join between relation R and relation S using the common attribute 'a' and retrieves all the tuples from relation R. However, this query may result in duplicate tuples if there are multiple tuples in S with the same value of attribute 'a'.
B. SELECT DISTINCT R.* FROM R, S WHERE R.a=S.a:
This option is similar to the previous option but eliminates duplicate tuples using the DISTINCT keyword. However, this query may be slower than the nested query as it involves sorting and removing duplicates from the entire result set.
C. SELECT R.* FROM R, (SELECT DISTINCT a FROM S) AS S1 WHERE R.a=S1.a:
This option uses a nested query to obtain a set of distinct values of attribute 'a' from relation S and then performs a natural join between relation R and the result of the nested query using the common attribute 'a'. This query will return the same result as the nested query in the question and is likely to be faster than option B.
D. SELECT R.* FROM R, S WHERE R.a=S.a AND IS UNIQUE R:
This option is not a valid SQL query as there is no such operator called IS UNIQUE in SQL. Moreover, it is unclear what the intention of this query is.
In conclusion, option C is the correct answer as it uses a nested query to obtain a set of distinct values of attribute 'a' from relation S and then performs a natural join between relation R and the result of the nested query using the common attribute 'a'. This query will return the same result as the nested query in the question and is likely to be faster than other options.
The nested query in the question selects all the tuples from relation R where the value of attribute 'a' is present in the set of values obtained by projecting attribute 'a' from relation S. The same result can be obtained using the following query options:
A. SELECT R.* FROM R, S WHERE R.a=S.a:
This option performs a natural join between relation R and relation S using the common attribute 'a' and retrieves all the tuples from relation R. However, this query may result in duplicate tuples if there are multiple tuples in S with the same value of attribute 'a'.
B. SELECT DISTINCT R.* FROM R, S WHERE R.a=S.a:
This option is similar to the previous option but eliminates duplicate tuples using the DISTINCT keyword. However, this query may be slower than the nested query as it involves sorting and removing duplicates from the entire result set.
C. SELECT R.* FROM R, (SELECT DISTINCT a FROM S) AS S1 WHERE R.a=S1.a:
This option uses a nested query to obtain a set of distinct values of attribute 'a' from relation S and then performs a natural join between relation R and the result of the nested query using the common attribute 'a'. This query will return the same result as the nested query in the question and is likely to be faster than option B.
D. SELECT R.* FROM R, S WHERE R.a=S.a AND IS UNIQUE R:
This option is not a valid SQL query as there is no such operator called IS UNIQUE in SQL. Moreover, it is unclear what the intention of this query is.
In conclusion, option C is the correct answer as it uses a nested query to obtain a set of distinct values of attribute 'a' from relation S and then performs a natural join between relation R and the result of the nested query using the common attribute 'a'. This query will return the same result as the nested query in the question and is likely to be faster than other options.
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SQL allows tuples in relations, and correspondingly defines the multiplicity of tuples in the result of joins. Which one of the following queries always gives the same answer as the nested query shown below:select * from R where a in (select S.a from S)a)select R.* from R, S where R.a=S.a (D)b)select distinct R.* from R,S where R.a=S.ac)select R.* from R,(select distinct a from S) as S1 where R.a=S1.ad)select R.* from R,S where R.a=S.a and is unique RCorrect answer is option 'C'. 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 SQL allows tuples in relations, and correspondingly defines the multiplicity of tuples in the result of joins. Which one of the following queries always gives the same answer as the nested query shown below:select * from R where a in (select S.a from S)a)select R.* from R, S where R.a=S.a (D)b)select distinct R.* from R,S where R.a=S.ac)select R.* from R,(select distinct a from S) as S1 where R.a=S1.ad)select R.* from R,S where R.a=S.a and is unique RCorrect answer is option 'C'. 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 SQL allows tuples in relations, and correspondingly defines the multiplicity of tuples in the result of joins. Which one of the following queries always gives the same answer as the nested query shown below:select * from R where a in (select S.a from S)a)select R.* from R, S where R.a=S.a (D)b)select distinct R.* from R,S where R.a=S.ac)select R.* from R,(select distinct a from S) as S1 where R.a=S1.ad)select R.* from R,S where R.a=S.a and is unique RCorrect answer is option 'C'. Can you explain this answer?.
SQL allows tuples in relations, and correspondingly defines the multiplicity of tuples in the result of joins. Which one of the following queries always gives the same answer as the nested query shown below:select * from R where a in (select S.a from S)a)select R.* from R, S where R.a=S.a (D)b)select distinct R.* from R,S where R.a=S.ac)select R.* from R,(select distinct a from S) as S1 where R.a=S1.ad)select R.* from R,S where R.a=S.a and is unique RCorrect answer is option 'C'. 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 SQL allows tuples in relations, and correspondingly defines the multiplicity of tuples in the result of joins. Which one of the following queries always gives the same answer as the nested query shown below:select * from R where a in (select S.a from S)a)select R.* from R, S where R.a=S.a (D)b)select distinct R.* from R,S where R.a=S.ac)select R.* from R,(select distinct a from S) as S1 where R.a=S1.ad)select R.* from R,S where R.a=S.a and is unique RCorrect answer is option 'C'. 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 SQL allows tuples in relations, and correspondingly defines the multiplicity of tuples in the result of joins. Which one of the following queries always gives the same answer as the nested query shown below:select * from R where a in (select S.a from S)a)select R.* from R, S where R.a=S.a (D)b)select distinct R.* from R,S where R.a=S.ac)select R.* from R,(select distinct a from S) as S1 where R.a=S1.ad)select R.* from R,S where R.a=S.a and is unique RCorrect answer is option 'C'. Can you explain this answer?.
Solutions for SQL allows tuples in relations, and correspondingly defines the multiplicity of tuples in the result of joins. Which one of the following queries always gives the same answer as the nested query shown below:select * from R where a in (select S.a from S)a)select R.* from R, S where R.a=S.a (D)b)select distinct R.* from R,S where R.a=S.ac)select R.* from R,(select distinct a from S) as S1 where R.a=S1.ad)select R.* from R,S where R.a=S.a and is unique RCorrect answer is option 'C'. Can you explain this answer? in English & in Hindi are available as part of our courses for Computer Science Engineering (CSE).
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SQL allows tuples in relations, and correspondingly defines the multiplicity of tuples in the result of joins. Which one of the following queries always gives the same answer as the nested query shown below:select * from R where a in (select S.a from S)a)select R.* from R, S where R.a=S.a (D)b)select distinct R.* from R,S where R.a=S.ac)select R.* from R,(select distinct a from S) as S1 where R.a=S1.ad)select R.* from R,S where R.a=S.a and is unique RCorrect answer is option 'C'. Can you explain this answer?, a detailed solution for SQL allows tuples in relations, and correspondingly defines the multiplicity of tuples in the result of joins. Which one of the following queries always gives the same answer as the nested query shown below:select * from R where a in (select S.a from S)a)select R.* from R, S where R.a=S.a (D)b)select distinct R.* from R,S where R.a=S.ac)select R.* from R,(select distinct a from S) as S1 where R.a=S1.ad)select R.* from R,S where R.a=S.a and is unique RCorrect answer is option 'C'. Can you explain this answer? has been provided alongside types of SQL allows tuples in relations, and correspondingly defines the multiplicity of tuples in the result of joins. Which one of the following queries always gives the same answer as the nested query shown below:select * from R where a in (select S.a from S)a)select R.* from R, S where R.a=S.a (D)b)select distinct R.* from R,S where R.a=S.ac)select R.* from R,(select distinct a from S) as S1 where R.a=S1.ad)select R.* from R,S where R.a=S.a and is unique RCorrect answer is option 'C'. Can you explain this answer? theory, EduRev gives you an
ample number of questions to practice SQL allows tuples in relations, and correspondingly defines the multiplicity of tuples in the result of joins. Which one of the following queries always gives the same answer as the nested query shown below:select * from R where a in (select S.a from S)a)select R.* from R, S where R.a=S.a (D)b)select distinct R.* from R,S where R.a=S.ac)select R.* from R,(select distinct a from S) as S1 where R.a=S1.ad)select R.* from R,S where R.a=S.a and is unique RCorrect answer is option 'C'. Can you explain this answer? tests, examples and also practice Computer Science Engineering (CSE) tests.
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