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copied!<p>You can make multiple calls to <code>mysql_connect()</code>, but if the parameters are the same you need to pass true for the '<code>$new_link</code>' (fourth) parameter, otherwise the same connection is reused. For example:</p> <pre><code>$dbh1 = mysql_connect($hostname, $username, $password); $dbh2 = mysql_connect($hostname, $username, $password, true); mysql_select_db('database1', $dbh1); mysql_select_db('database2', $dbh2); </code></pre> <p>Then to query database 1 pass the first link identifier:</p> <pre><code>mysql_query('select * from tablename', $dbh1); </code></pre> <p>and for database 2 pass the second:</p> <pre><code>mysql_query('select * from tablename', $dbh2); </code></pre> <p>If you do not pass a link identifier then the last connection created is used (in this case the one represented by <code>$dbh2</code>) e.g.: </p> <pre><code>mysql_query('select * from tablename'); </code></pre> <p><strong>Other options</strong></p> <p>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:</p> <ul> <li>Keep one connection open and call <code>mysql_select_db()</code> to swap between as necessary. I am not sure this is a clean solution and you could end up querying the wrong database.</li> <li>Specify the database name when you reference tables within your queries (e.g. <code>SELECT * FROM database2.tablename</code>). This is likely to be a pain to implement.</li> </ul> <p>Also please read troelskn's answer because that is a better approach if you are able to use PDO rather than the older extensions.</p>

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