Adding ORDER BY REGEXP possibilites

Example of use:
$MySqliDb->orderBy('name', 'desc', '^[a-zA-Z0-9]')->orderBy('name', 'desc');
// Is going to order by name but placing those name starting with special charaters at the end

MysqliDb.php

@@ -1061,16 +1061,16 @@ public function loadXml($importTable, $importFile, $importSettings = null)
     /**
      * This method allows you to specify multiple (method chaining optional) ORDER BY statements for SQL queries.
      *
-     * @uses $MySqliDb->orderBy('id', 'desc')->orderBy('name', 'desc');
+     * @uses $MySqliDb->orderBy('id', 'desc')->orderBy('name', 'desc', '^[a-z]')->orderBy('name', 'desc');
      *
      * @param string $orderByField The name of the database field.
      * @param string $orderByDirection Order direction.
-     * @param array $customFields Fieldset for ORDER BY FIELD() ordering
+     * @param mixed $customFieldsOrRegExp Array with fieldset for ORDER BY FIELD() ordering or string with regular expresion for ORDER BY REGEXP ordering
      * 
      * @throws Exception
      * @return MysqliDb
      */
-    public function orderBy($orderByField, $orderbyDirection = "DESC", $customFields = null)
+    public function orderBy($orderByField, $orderbyDirection = "DESC", $customFieldsOrRegExp = null)
     {
         $allowedDirection = Array("ASC", "DESC");
         $orderbyDirection = strtoupper(trim($orderbyDirection));
@@ -1086,13 +1086,16 @@ public function orderBy($orderByField, $orderbyDirection = "DESC", $customFields
             throw new Exception('Wrong order direction: ' . $orderbyDirection);
         }
 
-        if (is_array($customFields)) {
-            foreach ($customFields as $key => $value) {
-                $customFields[$key] = preg_replace("/[^-a-z0-9\.\(\),_` ]+/i", '', $value);
+        if (is_array($customFieldsOrRegExp)) {
+            foreach ($customFieldsOrRegExp as $key => $value) {
+                $customFieldsOrRegExp[$key] = preg_replace("/[^-a-z0-9\.\(\),_` ]+/i", '', $value);
             }
-
-            $orderByField = 'FIELD (' . $orderByField . ', "' . implode('","', $customFields) . '")';
-        }
+            $orderByField = 'FIELD (' . $orderByField . ', "' . implode('","', $customFieldsOrRegExp) . '")';
+        }elseif(is_string($customFieldsOrRegExp)){
+	    $orderByField = $orderByField . " REGEXP '" . $customFieldsOrRegExp . "'";
+	}elseif($customFieldsOrRegExp !== null){
+	    throw new Exception('Wrong custom field or Regular Expression: ' . $customFieldsOrRegExp);
+	}
 
         $this->_orderBy[$orderByField] = $orderbyDirection;
         return $this;