Activerecord PG Update From Select

Question

I have a table that i need to add a new field and copy the value into another field. Now this table has way to many records so i can just loop on each record and update it one at the time.

What would be the best way to do this.

My DB is PG but i would really like a Activerecord way of doing this

Answer 1

YourTable.update_all('new_field_name = old_field_name')

see http://apidock.com/rails/ActiveRecord/Base/update_all/class