Varchar 2 - change length semantics

Hi,
I have got a question:
Imagine situation you have got a huge DB, where all tables are created with nls_length_semantics set as BYTE (The default). Then you find out, you in fact need all of the Varchar2 columns to have the specified length in CHARs. Is there any simple way how to update all existing columns to length as if it was defined with the CHAR setting, or do I have to alter each table separately?

Thanks

Create a script for alter and run it .

Thanks a lot.