SQL & PL/SQL :: Find The Longest Path

create table test
(
avarchar2(10),
bvarchar2(10)
)
/
insert into test values ('A', 'B');

[Code]...

We want to get the path from "A" to "E". In other words, if we start with any value of the column "a" we have to reach the "maximum" value of the column "b".

"maximum" in sense that we don't find the value of "b" in "a".

Example :
---------
E is not found in the column a, so E is the maximum of A.
- N is the maximum of K
- Z is the maximum of Q and the maximum of S

select ...
from ...
where a = 'A' should return E.