advanced SQL question

there is f.e. the following table:

NAME     FROM   TO   LENGTH
123456   O      A    10      *
123456   A      B    15      *
123456   B      C    10      *
123456   C      O    20      *
123456   B      F    50
654321   O      A    20
654321   A      B    30

in the knode 123456 is a circle OABCO (see the *) and BF outside of this circle (all circles start with 'O').
knode 654321 has no circle at all.

I need the result
NAME CIRCLE CIRCLELENGTH
123456 OABCO 55 Is there a way to do this via SQL or do I need PLSQL?

Thanks in advance
Andreas

-- 
wenn email, dann AndreasMosmann <bei> web <punkt> de