How do you connect to multiple MySQL databases on a single webpage?

You can make multiple calls to mysql_connect(), but if the parameters are the same you need to pass true for the '$new_link' (fourth) parameter, otherwise the same connection is reused.

so then you have

$dbh1 = mysql_connect($hostname, $username, $password);
$dbh2 = mysql_connect($hostname, $username, $password, true);

mysql_select_db('database1', $dbh1);
mysql_select_db('database2', $dbh2);

Then to query database 1, do

mysql_query('select * from tablename', $dbh1);

and for database 2

mysql_query('select * from tablename', $dbh2);

Alternatively, if the mysql user has access to both databases and they are on the same host (i.e. both DBs are accessible from the same MySQL connection) you could:

Example :

$migglecon = mysql_connect("localhost","root","123");
mysql_select_db("thefarmyard",$migglecon)or die(mysql_error());


$drupalcon= mysql_connect($localhost,$root,$123,true);
mysql_select_db("miggle",$drupalcon)or die(mysql_error());