Custom MySQL Function

I really NEED the mysql_num_rows() functionality in v.6.19 so I figured I could just add it back.

I edited includes/database.mysql.inc, and added:

function db_num_rows($result) {
 $array = mysql_num_rows($result);
 return $array[0];
}

However when I try to use db_num_rows($query) I get the error: "Call to undefined function db_num_rows()"

How can I re-instate mysql_num_rows() in my 6.x installation?

Thanks.

PS: The db_result() alternatives do not seem to work on complex queries, like this one ...

"SELECT DISTINCT(users.uid) AS uid_1,
users.uid AS uid,
users.name AS users_name,
users.mail AS users_mail,
users.picture AS users_picture,
profile_values_profile_name.value AS profile_values_profile_name_value,
profile_values_profile_name.uid AS profile_values_profile_name_uid,
profile_values_profile_address.value AS profile_values_profile_address_value,
profile_values_profile_city.value AS profile_values_profile_city_value,
profile_values_profile_state.value AS profile_values_profile_state_value,
profile_values_profile_zip.value AS profile_values_profile_zip_value,
profile_values_profile_description.value AS profile_values_profile_description_value,
userpoints.points AS userpoints_points,
comments.uid AS comments_uid,
comments.cid AS comments_cid,
comments.subject AS comments_subject,
comments.comment AS comments_comment
 FROM users users 
 LEFT JOIN profile_values profile_values_profile_name ON users.uid = profile_values_profile_name.uid AND profile_values_profile_name.fid = '12'
 LEFT JOIN profile_values profile_values_profile_address ON users.uid = profile_values_profile_address.uid AND profile_values_profile_address.fid = '14'
 LEFT JOIN profile_values profile_values_profile_city ON users.uid = profile_values_profile_city.uid AND profile_values_profile_city.fid = '15'
 LEFT JOIN profile_values profile_values_profile_state ON users.uid = profile_values_profile_state.uid AND profile_values_profile_state.fid = '16'
 LEFT JOIN profile_values profile_values_profile_zip ON users.uid = profile_values_profile_zip.uid AND profile_values_profile_zip.fid = '17'
 LEFT JOIN profile_values profile_values_profile_description ON users.uid = profile_values_profile_description.uid AND profile_values_profile_description.fid = '20'
 LEFT JOIN userpoints userpoints ON users.uid = userpoints.uid
 LEFT JOIN comments comments ON users.uid = comments.uid
 WHERE LENGTH((profile_values_profile_name.value)) > 0
 GROUP BY uid_1
  ORDER BY userpoints_points DESC
  LIMIT 5";

I unsuccessfully tried several arrangements, like:

"SELECT DISTINCT(users.uid) AS uid_1,
COUNT(DISTINCT(users.uid)) AS uid_count,
 ...

and then

$result = db_result(db_query($query));

and then

while($row = db_fetch_array($result)) {
$uid_count = $row['uid_count'] ...

or

while($row = db_fetch_object($result)) {
$uid_count = $row->uid_count ...

In this situation, $uid_count always ends up as '1'.

If I could just do "$uid_count = mysql_num_rows($query)" I would be happy.