Hi,
 
thanks for all your answers.
I'll have a try with the contains operator and the intrange, but before I'd like to know if this would work:
 
CASE WHEN a >= 0 AND a < 25
CASE WHEN a >= 25 AND a < 50
 
There wouldn't be a double endpoint. I just have to decide which range the endpoint includes.
 
Janek Sendrowski