问题
If I change an existing column type from varchar2 to nvarchar2 in Oracle will Oracle automatically convert existing column data between character set or should I do it myself?
I'm using Oracle 11g, the varchar2 character set is WE8MSWIN1252 and the nvarchar2 character set is AL16UTF16
回答1:
You can use the package DBMS_REDEFINITION for doing the changing the varchar2 to nvarchar2 column for a table
Please find the below link which might be helpful
Using Online Table Redefinition to Migrate a Large Table to Unicode
Also find the documentation for General Character set Migration
General Character set Migration
来源：https://stackoverflow.com/questions/11412982/oracle-varchar2-to-nvarchar2-conversion