What is this hacker trying to do?

Question

If you do a search for:

http://www.google.co.uk/search?q=0x57414954464F522044454C4159202730303A30303A313527&hl=en&start=30&sa=N

you will see a lot of

Answer 1

According to http://bytes.com/topic/mysql/answers/888849-hacker-attempt it looks like it's trying to run:

WAITFOR DELAY '00:00:15'

As others have pointed out it's not a DOS attack (as I originally stated) but merely a way to easily determine if the SQL Server is vulnerable and can be added to a list of hosts to perhaps further hack away at later on.