made easy test series

Question

Answer 1

both the queries will return the same result as in first query it is easily visible that it is intersection and in query 2 nested query 2 will return all p tuples and nested query 1 will return tuples of r which is not similar to tuples return by nested query 2 and finally main query will return all those tuples which are common in both the relations

and your answer is yes it will eliminate as it will only return the intersected part which is present in both.

Comments

But intersection all

Union all doesn't remove duplicate