For example, i've added an user by hand, password hash is:

33cfc0eebba3737b243574315b1bc302fc4222b5

and the check is done by:

if($result = $mysqli->query("Select * from utenti where username='".$mysqli->real_escape_string($_POST['username'])."' and password=sha1('".$mysqli->real_escape_string($_POST['password'])."')")){

so the sha1 function is mysql function, and the query works fine..
now sha1 created by mysql are like:

64376437383463653536363537306661333538626164356539346333626365386264653739356532

so much longher.. and there are no hex digits like abcdef...