Part of the problem here is that there isn't any particular DBMS independent way of checking whether a database exists - you may be able to use the DBI data_sources method, however some database systems (such as SQLite) don't necessarily know this information, others (such as Informix and MS SQL Server) might allow you to query a table such as sysdatabases. So data_sources() might be your man but it definitely comes with some caveats.

/J\