Design SQL queries that return each of the following expressions, assuming that R and S are tables representing the relations R and S, respectively: (i) R [ S, (ii) R \ S (iii) R ???? S, (iv) R / S.
For (i) to (iii), you may also assume that R and S are union compatible. For (iv), you may
assume that S has attributes b1, ..., bm, and R has in addition attributes a1, ...,
an.
i. SELECT * FROM R UNION SELECT * FROM S
ii. SELECT * FROM R INTERSECT SELECT * FROM S
iii. SELECT * FROM R EXCEPT SELECT * FROM S
iv. SELECT a1,...,an
FROM R R1
WHERE NOT EXISTS(
SELECT * FROM S
EXCEPT
SELECT R2.b1,...,R2.bm
FROM R R2
WHERE R1.a1=R2.a1 AND ... AND R1.an=R2.an)
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