One database using most of the CPU

Question

HI,
On one of our SQL server, the CPU was really high. I ran a query to find out which database was using most of the CPU. We have about 30 databases on that server. 
Database 1 is using 90% of the CPU 
Database 2 3.5%
Database 3 1.5%.
etc...
The database 1 in our Intranet and i really don't understand why it's using all the CPU available. We have just a few people connected at once. 
I'd like to know if there's any way to find out why that database is using all the CPU? Memory leak, bad code, etc...
Thank you

Answer 1

---This first thing to check if CPU is at 100% is to look for parallel queries:
-- Tasks running in parallel (filtering out MARS requests below):
select * from sys.dm_os_tasks as t
 where t.session_id in (
   select t1.session_id
    from sys.dm_os_tasks as t1
   group by t1.session_id
  having count(*) > 1
  and min(t1.request_id) = max(t1.request_id));
-- Requests running in parallel:
 select *
   from sys.dm_exec_requests as r
   join (
           select t1.session_id, min(t1.request_id)
          from sys.dm_os_tasks as t1
         group by t1.session_id
        having count(*) > 1
           and min(t1.request_id) = max(t1.request_id)
      ) as t(session_id, request_id)
     on r.session_id = t.session_id
Best Regards,Uri Dimant SQL Server MVP,
http://sqlblog.com/blogs/uri_dimant/
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