Oracle nested query

Question

Essentially I'm attempting to select the top read (based on read_date), and check if it has a type in ( 'R','S','C','B','Q','F','I','A')

select *
from (
 select *
 from (
 select *
 FROM table
 WHERE id = 369514
 order by read_date desc
 )
 where rownum = 1
 )
 where type IN ( 'R','S','C','B','Q','F','I','A')

I only need to return a row if the top row has a type in the set, if not return nothing.

The only way I seem to be able to is using all these nasty sub-queries.

• Malachi: is this Query slow? is it inefficient?
• m.edmondson: not slow, just looked like it could probably be improved

Answer 1

I was looking at the Query and you should be able to get rid of the outside Select.

select *
from (
 select *
 FROM table
 WHERE id = 369514
 order by read_date desc
 )
where rownum = 1 AND type IN ( 'R','S','C','B','Q','F','I','A')

I don't have anything to Test against, but it looks like this would work.

• m.edmondson: I've actually realised this myself and removed it. I've upvoted :-)