Select between two databases

Hi,

Does any one know how I may select between two databases running on same
machine or on different machines eg.

select colA1 from tableA1 where colA2 in (select colB1 from tableB1);

here tableA1 and tableB1 are in different databases. The two databases
might be under the same postmaster or on different machines under
different postmasters. How do I query both simultaneously? Is it possible?

Thanks,
Indraneel

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# Indraneel Majumdar ¡ E-mail: indraneel(at)123india(dot)com #
# Bioinformatics Unit (EMBNET node), ¡ URL: http://scorpius.iwarp.com #
# Centre for DNA Fingerprinting and Diagnostics, #
# Hyderabad, India - 500076 #
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