md5 encryption

[eluser]junaids[/eluser]
hi i have a registration module and i save user password using md5 encryption.
then on login i use md5 to encrypt the password and match it with database.
but it does not match

Code:

$this->db->from('user');
$this->db->where('username',$u);
$this->db->where('password', md5($pw));
echo md5($pw);

against a particular username and password with the echo statement i m getting pw as "7fa8282ad93047a4d6fe6111c93b308a "
while in the db the password is "7fa8282ad930"

the password in the db is just a part of password produced on login so i m unable to login why?