Last 10 records of a table

[Steffen Lindauer]

Hello,
 
i'm searching for a solution, getting the last 10 records of a
database. I've got a table with timestamps and corresponding values.
 
SELECT ts,value FROM table WHERE rowno <= COUNT(*)-10''; doesn't work,
can sb help me plz?
 
I have no idea :(
 
Thx, Steffen