For all cases where the same reviewer rated the same movie twice and gave it a higher rating the second time, return the reviewer's name and the title of the movie.

how to understand these SQL query?

select Reviewer.name, Movie.title from Reviewer, Movie, (select R1.rID, R1.mID from Rating R1, Rating R2 where R1.rID=R2.rID and R1.mID=R2.mID and R2.ratingDate>R1.ratingDate and R2.stars>R1.stars) as T where Reviewer.rID=T.rID and Movie.mID=T.mID

expecially,why add"()" here???thank u!