Oracle DBID what is logic to create oracle DBID?
DBID is a numeric identifier that utilities like RMAN use to identify databases.

You can get your DBID like this:

select DBID from v$database;


However it NOT unique especially if you have copies of your database where you hot start them with:

recover database until change &lt;SCN&gt; using backup controlfile;


but if you don't have (control file) copies, then it is unique.  

Because it's a number it's not a nice way to uniquely identify databases.

What we do to uniquely identify our databases across the whole company, is to create TNS entries in the form of "SID.host" because SID is unique on the host, and then use this format in our global tnsnames.ora.