Two tables and one query?

Is it possible to call fields from two different tables in one query?

Ex. (I know this particular example doesn't work)

$query = "SELECT variable, FROM database_one WHERE variable='Blah' AND SELECT variable_two FROM database_two WHERE variable_two='BlahBlah'";

thanks in advance

 

$query = "SELECT variable FROM database_one WHERE variable='Blah' UNION SELECT variable_two FROM database_two WHERE variable_two='BlahBlah'";

 

Thank you very much

What about when using randomization?

eg. (this doesn't work) $query = "SELECT variable FROM database_one ORDER BY RAND() LIMIT 1 UNION SELECT variable_two FROM database_two ORDER BY RAND() LIMIT 1"

 

ORDER BY does not work within UNION. But you can apply it to the whole results.