Simple query question

[eluser]markanderson993[/eluser]
Hello there codeigniter experts! I have a small and simple question. I am entering this code

Code:

$second_verify = $this->CI->db->query("
                SELECT *
                FROM user
                WHERE
                    user_name = " . $username_login . " and
                    password = md5(concat(md5(" . $password_login . "), salt))
            ");

And I keep getting this error:

A Database Error Occurred

Error Number: 1054

Unknown column 'pianoman993' in 'where clause'

SELECT * FROM user WHERE user_name = pianoman993

I know the solution must be incredibly simple but I just can't figure it out! Does anyone have any ideas?

Any help would be greatly appreciated!
Thank you!

- Pianoman993