The following file will allow you to alter the table prefix used in your site.
Once this script has run you do need to alter the config.php to reflect the change.

Upload the file to your fusion site base directory
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Assume no Error - Open config.php
Assume no Error - Alter prefix to suit new prefix.
Assume no Error - remove this file from server. File written by Ausimods

<?php /** * @name prefix_changer.php * @access ALL * @author AusiMods @ < ausimods.com > * @copyright GPL * @package php-fusion * @subpackage External table prefix changer */ switch (isset($_POST['op']) && $_POST['op'] == 'go' ? $_POST['op'] : NULL) { case 'go': $new_prefix = isset($_POST['prefix']) ? $_POST['prefix'] : "fusion_"; if(file_exists('config.php')) { require_once "config.php"; } else { die('Incorrect file location'); } if (!mysql_connect($db_host, $db_user, $db_pass)) { die('Could not connect to mysql'); } $sql = "SHOW TABLES FROM $db_name"; $result = mysql_query($sql); if (!$result){ echo "Cant Find the tables<br />\n"; print(mysql_error()); exit; } while ($row = mysql_fetch_row($result)){ $rename = ereg_replace(DB_PREFIX, $new_prefix, $row[0]); $change = @mysql_query("RENAME TABLE `{$db_name}`.`{$row[0]}` TO `{$db_name}`.`{$rename}` ;"); if($change) { echo "SUCCESS ON: {$row[0]} to {$rename}<br />\n"; } else{ echo "FAILURE ON: {$row[0]} to {$rename}<br />\n"; } } mysql_free_result($result); echo 'Pretty sure the task is complete.<br /> Open config.php and alter the current prefix to your new one to re enable your site.'; break; default: echo '<form method="post" action="">'; echo '<input type="hidden" name="op" id="op" value="go" />'; echo 'Change table prefix to <input type="text" name="prefix" id="prefix" value="" />.'; echo '<input type="submit" name="submit" id="submit" value="submit" />'; echo '</form>'; break; } ?>