Order by field support

MysqliDb.php

@@ -446,7 +446,7 @@ class MysqliDb
      *
      * @return MysqliDb
      */
-    public function orderBy($orderByField, $orderbyDirection = "DESC")
+    public function orderBy($orderByField, $orderbyDirection = "DESC", $customFields = null)
     {
         $allowedDirection = Array ("ASC", "DESC");
         $orderbyDirection = strtoupper (trim ($orderbyDirection));
@@ -455,6 +455,13 @@ class MysqliDb
         if (empty($orderbyDirection) || !in_array ($orderbyDirection, $allowedDirection))
             die ('Wrong order direction: '.$orderbyDirection);
 
+        if (is_array ($customFields)) {
+            foreach ($customFields as $key => $value)
+                $customFields[$key] = preg_replace ("/[^-a-z0-9\.\(\),_]+/i",'', $value);
+
+            $orderByField = 'FIELD (' . $orderByField . ', "' . implode('","', $customFields) . '")';
+        }
+
         $this->_orderBy[$orderByField] = $orderbyDirection;
         return $this;
     } 

readme.md

@@ -266,6 +266,13 @@ $results = $db->get('users');
 // Gives: SELECT * FROM users ORDER BY id ASC,login DESC, RAND ();
 ```
 
+order by values example:
+```php
+$db->orderBy('userGroup', 'ASC', array('superuser', 'admin', 'users'));
+$db->get('users');
+// Gives: SELECT * FROM users ORDER BY FIELD (userGroup, 'superuser', 'admin', 'users') ASC;
+```
+
 ### Grouping method
 ```php
 $db->groupBy ("name");

tests.php

@@ -149,6 +149,14 @@ if ($db->count != 3) {
     exit;
 }
 
+// order by field
+$db->orderBy("login","asc", Array ("user3","user2","user1"));
+$login = $db->getValue ("users", "login");
+if ($login != "user3") {
+    echo "order by field test failed";
+    exit;
+}
+
 $db->where ("active", true);
 $users = $db->get("users");
 if ($db->count != 1) {