[Tuesday, April 25, 15:25]

> I am doing the final exam of SPRINT 1999.
> I have few quick question
> 1. for exercise 1 (b)
> the solution is
> SELECT P.ID,P.PATH
> FROM PAGE P
> WHERE P.ID NOT IN (SELECT R.ID
>                    FROM REQUEST
>                    WHERE WHEN >='01-JAN-99')
>
> I don't know do we need to add R for REQUEST in sebquery, and the new
> subquery is
> (SELECT R.ID
> FROM REQUEST R
> WHERE WHEN >='01-JAN-99')

Yes. You are right. If the tuple variable R is used, it must be declared.

> and the other question is for 1 (a)
> do we need to add DISTINCT into select-clause?            

No, if I am not mistaken, every solution will be printed only once.
P.ID is the key of the page table.
For X and Y we are given ID and the Word, which means for a given page P,
there can be at most one solution for X and Y.