how CTE help in solving herirecal routes

Question

fr_city   to_city

A              B

A             C

B            D

C            D

E             C

A             D

C             E

 

above table shows routes between  different cities ,

how i can get all possible  path  between city A and D , 

e.g

1) A ----> D

1)A-----> B------>D

3) A----> C ------> D

 

what i want to do is to give origin city and destination city ,

Can with help of common table expression  we calculate all possible  ways to go  to destination 

 

please help

Answer 1

there is solutio given in below link 

 

http://technology.amis.nl/blog/1221/building-a-route-planner-with-oracle-sql-finding-the-quickest-route-in-a-graph

but i am not visualize  the solution ,

any help is will be highly appropriated ...