How can I duplicate a field?

I have a table with two fields, and i need to duplicate one field in another one with different name but same data

is it possible via phpmyadmin or so?

assuming i have

user_id |  user_name

i need to have

user_id |  user_name | user_name2

where user_name has same data as user_name2

what is the fastest way? is just for some experiment purpose so don开发者_如何学Pythont comment on why i'm doing it thanks

update table_name set user_name2= user_name