Query Rewrite:
Predicate Movearound
Create View V1 AS
Select   rating, Min(age)
From    Sailors S
Where  S.age < 20
Group By  rating
Create View V2 AS
Select   sid, rating, age, date
From    Sailors S, Reserves R
Where  R.sid=S.sid
Select   sid, date
From    V1, V2
Where   V1.rating = V2.rating  and
              V1.age = V2.age
Sailing wiz dates: when did the youngest of each sailor level rent boats?