create own datatypes

Hello to all!

Is there the possibility in oracle to create my own datatype (no objects or records)?
I want to do the following:

create DTusername = varchar(30) //my own datatype

Then i want to use DTusername for example in one table:

create table test_table ( username DTusername );

The advantage of this method is that everybody who create his table is using for username automatically varchar(30), and every table has the same type.
In Sybase there is i think the possibility. in borlands interbase it works with create domain.
I asked specialists, but nobody knows or they say it doesn't work.

Thank you for answering,
Markus Received on Thu Sep 06 2001 - 09:08:19 CDT