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.
For example:
$dbh1 = mysql_connect($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 pass the first link identifier:
mysql_query('select * from tablename', $dbh1);
and for database 2 pass the second:
mysql_query('select * from tablename', $dbh2);
If you do not pass a link identifier then the last connection created is used (in this case the one represented by $dbh2) e.g.:
mysql_query('select * from tablename');
Other options
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 connection) you could:
- Keep one connection open and call
mysql_select_db()to swap between as necessary. I am not sure this is a clean solution and you could end up querying the wrong database. - Specify the database name when you reference tables within your queries (e.g.
SELECT * FROM database2.tablename). This is likely to be a pain to implement.