added MongoStatement class, modified DbDriver hierarchy

model/DbDriver.php

@@ -49,6 +49,23 @@ abstract class DbDriver
         return $this->connection;
     }
 
+    /**
+     * @param mixed $request
+     * @param mixed $params
+     * @return DbStatement
+     */
+    public function query($request, $params = array())
+    {
+        $this->connect();
+        if (!is_array($params)) {
+            $params = array($params);
+        }
+        $stmt = $this->prepare($request);
+        $stmt->execute($params);
+        return $stmt;
+    }
+    
+
     /* Abstract methods  */
 
     abstract public function insert($table, $data);
@@ -56,6 +73,8 @@ abstract class DbDriver
     abstract public function update($table, $data, $condition);
     
     abstract public function delete($table, $condition);
+
+    abstract public function prepare($request);
     
     abstract public function getInsertId($table = null, $key = null);