In this case you don't need joins because you're retrieving data from one table only. If you pull data from multiple tables than in most cases you'll have to join them.
The Exists type subquery is usually faster than joining tables. I think that my query should be faster but I could be wrong. The only way to be sure of impact is to run both queries and compare execution time.

>I see how your example would work Sergey but if this is the case then why bother with inner and outer joins? Is there a performace loss using your method rather then using joins? Just curious as to what the impact is (if any).