CODEIGNITER 3 : A Database Error Occurred

Question

I am a to do CodeIgniter authentication, but I get an error:

A Database Error Occurred
Error Number: 1064
You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '.*,'user_menu'.'menu' FROM 'user_sub_menu' JOI' at line 1 SELECT 'user_sub_menu'.*,'user_menu'.'menu' FROM 'user_sub_menu' JOIN 'user_menu' ON 'user_sub_menu'.'menu_id' = 'user_menu'.'id'

And this is my code

public function getSubMenu()
{
    $query = "SELECT 'user_sub_menu'.*,'user_menu'.'menu'
            FROM 'user_sub_menu'
            JOIN 'user_menu'
            ON 'user_sub_menu'.'menu_id' = 'user_menu'.'id'
            ";
    return $this->db->query($query)->result_array();
}