Query in codeigniter

Hello, i'm trying to compare a date from database with my variable. But doesn't work.

PHP Code:

           $query = $this->db->get('chamadas');
            $this->db->select("*,DATE_FORMAT(data_chamada, '%d-%m-%Y') as 'data_chamada'");
            $this->db->from('chamadas');
            $this->db->where("DATE_FORMAT(data_chamada, '%d-%m-%Y') as data_chamada", $codigo);
            $query = $this->db->get();
            return $query->result(); 


A Database Error Occurred

Error Number: 1064

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'as data_chamada '06-08-2015'' at line 3

SELECT *, DATE_FORMAT(data_chamada, '%d-%m-%Y') as 'data_chamada' FROM `chamadas` WHERE DATE_FORMAT(data_chamada, '%Y-%m-%d') as data_chamada '06-08-2015'

Filename: C:/wamp/www/projetowebconf/application/models/historico_model.php

Line Number: 13


Can anyone help me?

I got it.
I fomated my date before query.

$date = date("Y-m-d", strtotime($codigo));