SQL allows duplicate 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 R.* from R,S where R.a = S.a and is unique R

select distinct R.* from R, S where R.a = S.a

select R.* from R, (select distinct a from S) as S1

SQL allows duplicate tuples in relations, and correspondingly defines

1.	SQL allows duplicate 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 :
A.	select distinct R.* from R, S where R.a = S.a
B.	select R.* from R, (select distinct a from S) as S1
C.	where R.a = S1.a
D.	select R.* from R,S where R.a = S.a and is unique R
Answer» D. select R.* from R,S where R.a = S.a and is unique R

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SQL allows duplicate 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 :

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