Format of Date/Time when using ActiveRecord with Oracle Database

I found no place in ActiveRecord Documentation, that describes how to enter Date/Time into Oracle Database. By looking at source code of OracleAdapter in ActiveRecord, I recognized that ActiveRecord uses Oracle alter session command to specify date format

ActiveRecord::Base.connection.execute "alter session set NLS_DATE_FORMAT='YYYY-MM-DD HH24:MI:SS'"

As implication we shall use this format (e.g '2007-06-30' and '2007-06-30 23:01:45' String are accepted) when entering data (e.g in fixture file) to Date Field.