Is it possible : Change color on database field

[Stéphane RIFF]

What i want to do is :
  I represent gps track on a map, this work fine with one class and one
color.
 I want mapserver to change the symbol color each time ths vehicles stop
and start again
in the database it's a field that match speed. So each time the speed
field is equal to zero
i want to change the color.
I don't know how to do that , is it possible ??? How ???

Hope i'm understandable
Thanks