$sql = "UPDATE `glpi_plugin_customfields_fields`\n                    SET `deleted` = 1,\n                        `system_name` = 'DELETED',\n                        `sort_order` = 0,\n                        `dropdown_table` = ''\n                    WHERE `itemtype` = '{$itemtype}'\n                          AND `id` = '" . intval($id) . "'\n                          AND `system_name` = '{$system_name}'";
         } else {
             // Nothing in the history log, so delete the field completely
             $sql = "DELETE\n                    FROM `glpi_plugin_customfields_fields`\n                    WHERE `itemtype` = '{$itemtype}'\n                          AND `id` = '" . intval($id) . "'\n                          AND `system_name` = '{$system_name}'";
         }
         // Remove the custom field from the data table
         $result = $DB->query($sql);
         $table = plugin_customfields_table($itemtype);
         $sql = "SELECT COUNT(`id`) AS num_left\n                 FROM `glpi_plugin_customfields_fields`\n                 WHERE `itemtype` = '{$itemtype}'\n                       AND `data_type` <> 'sectionhead'\n                       AND `deleted` = 0";
         $result = $DB->query($sql);
         $data = $DB->fetch_assoc($result);
         if ($data['num_left'] == 0) {
             // If no more fields, drop the data table
             $sql = "DROP TABLE IF EXISTS `{$table}`";
             // ...and disable the device
             plugin_customfields_disable_device($itemtype);
         } else {
             // Remove the column from the data table
             $sql = "ALTER TABLE `{$table}`\n                    DROP `{$system_name}`";
         }
         $result = $DB->query($sql);
     }
     // Done. Reload.
     Html::redirect($_SERVER['HTTP_REFERER']);
 } else {
     if (isset($_POST['add'])) {
         // Add a field
         $data_ok = false;
         $sort = intval($_POST['sort']);
         if (isset($_POST['dropdown_id'])) {
             // Add a drop down menu
 /**
  * Unregister an item type brought by an other plugin
  *
  * @param $itemtype
  * 
  */
 static function unregisterItemType($itemType)
 {
     global $DB;
     // Check if the itemtype has already been registered
     $query = "SELECT `enabled`\n      FROM `glpi_plugin_customfields_itemtypes`\n      WHERE `itemtype` = '{$itemType}'";
     $result = $DB->query($query);
     if ($DB->numrows($result) != 0) {
         // The itemtype must be disabled before unregistration
         //  Has no effect if the itemtype is not enabled
         plugin_customfields_disable_device($itemType);
         // The new item type needs to be unregistered
         // Remove the fields definition for the itemtype being deleted
         $query = "DELETE FROM `glpi_plugin_customfields_fields`\n                    WHERE `itemtype` = '{$itemType}'";
         $result = $DB->query($query) or die($DB->error());
         // Remove the itemtype from the itemtypes supported by the plugin
         $query = "DELETE FROM `glpi_plugin_customfields_itemtypes`\n                    WHERE `itemtype` = '{$itemType}'";
         $result = $DB->query($query) or die($DB->error());
         // Remove all data for the itemtype
         $table = plugin_customfields_table($itemType);
         if ($table) {
             $query = "DROP TABLE IF EXISTS `{$table}`";
             $DB->query($query) or die($DB->error());
         }
         // Unregister the itemtype
         $query = "DELETE FROM `glpi_plugin_customfields_itemtypes`\n         WHERE `itemtype` = '{$itemType}'";
         $DB->query($query) or die($DB->error());
     }
 }