Connection to multiple databases

hi,

how can I solve following problem:
On a standalone Linux-PC I wish to locate several
databases in the directory ../pgsql/data, viz:

1. readers_DATABASE with about 20 tables
the readers_TABLE has follwing fields:
readers_id
readers_name
...
...

2. publication_DATABASE with about 40 tables
the publication_TABLE has following fields:
publication_id
publication_description
readers_id
...
...

3. other_DATABASE
4. ...

Is it possible to make following query:

SELECT publication_description FROM publication_DATABASE.publication_TABLE
WHERE publication_DATABASE.publication_TABLE.readers_id =
readers_DATABASE.readers_TABLE.readers_id;

or have I to put all tables in one database.

Thanks
b-bakowski(at)web(dot)de

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