From Postgres docs http://www.us.postgresql.org/users-lounge/docs/7.2/postgres/datatype-datetime.html

Date and time input is accepted in almost any reasonable format, including ISO 8601, SQL-compatible, traditional PostgreSQL, and others.

I don't know about Oracle, but any modern (or not so modern) database engine should provide either a standard time format, or has a function to convert to the time format you want.

Hope this helps,,,