I would like to know if there is any tool able to extract the design from an existing Oracle database.
I have a read access to it and I would like to have the design. Or simply export it to a *.sql and then read it with any tool able to create the design with the links between the tables.
Something like that 
(source: fileguru.com)
Thank you very much.
There are a number of tools which do reverse engineering from an Oracle database, but most require a license.
Oracle has its own Data Modeller. Previously Oracle tried to charge an exorbitant licence fee but obviously they had few takers because it is now free. It is not a great product but it does a decent job on reverse engineering.
If you are a site which uses TOAD then you should definitely consider Quest's TOAD Data Modeler. The additional cost is not a great stretch from the basic TOAD fee.
There are not many other free tools left on the market but SQL Power offer a community edition of their SQL Architect tool which does reverse engineering. Check it out.
Oracle SQL Data Modeler answered to all my questions.
It has a reverse engineering tool that creates the logical and physical model from the database.
来源：https://stackoverflow.com/questions/3474107/reverse-engineer-database-from-an-oracle-database