Database Evolution & Change of Database Name

Hi all, I have a few questions regarding to database evolution, hope you can help. Thank you in advance. One of the main objective for my database upgrade is to cut down the systems outage time because the database that i working on is a very huge. The following is the proposal that i'm working on: a) Duplicate the existing database A to database A". b) Run the database evolution and upgrade program to change database A" schemas while the old application is still running. c) Upon completion of upgrade in (b), shutdown the old application and modify the application symbolic links. d) Rename the database A" to database A. e) Brings up the new application. By then the new application will refers to new database A schemas I'm not sure what i proposed is feasible for implementation. How you can provide me your expertise help and comments. Besides, can you provide me the different between dbexport and dbimport and how they can help me in this context (see my proposal above). Please do let me know if you have other better suggestions for me. Thank you once again. Have a nice day, kitming