How do I get a list of DB's or Tables with a postgres SQL statement?

All,

How do I get a list of DB's or Tables with a postgres SQL statement?
It needs to be an SQL statement otherwise perl/DBI/prepare won't parse it.
I know there is some funtions in psql:

\l    (show databases)
\d    (show tables)

which work fine from psql, but these
statements won't be parsed by perl, DBI

I also know there is an object:

@names = $dbh->tables;

but what about databases?

Please help.

Ron de Jong
the Netherlands