Editing Core Modules

Hi

I am still having problems with this. I am using an update hook and, when i make a function call to my function in my module from the user module, it works. However, i do not want to use alter the core user module because of issues during possible upgrading of Drupal.

I have tried using a user hook, but this doesnt fire off my code at all and I dont understand why (my knowledge of hooks is limited). Am i right in making the assumption that my code isn't firing because there is no obvious place for it to be fired?

I have attached the code below for my module:-

<?php
// $Id: moodle_user.module,v 1.612.2.21 2006/10/18 20:14:42 killes Exp $

function moodle_user($op = 'update') {

if ($op == 'update' || $op == 'insert')
{

//query first database
$results = db_query('SELECT abhachudrupal.users.name, abhachudrupal.users.uid FROM abhachudrupal.users, abhachudrupal.users_roles WHERE abhachudrupal.users.uid = abhachudrupal.users_roles.uid and abhachudrupal.users_roles.rid=3');

db_set_active('moodle');

//count the number of record in the admins table
$results4 = db_query('SELECT * FROM abhachu.mdl_user_admins');
$row4 = mysql_num_rows($results4);
//echo "num:-";
//echo $row4;
//echo "
";

//create a duplicates table
$create = db_query('CREATE TABLE abhachu.mdl_dup_admins (id INTEGER(10) NOT NULL auto_increment, userid INTEGER(10) NOT NULL, PRIMARY KEY(id))');

//To echo(display) results
while ($row = mysql_fetch_array ($results))
{
extract ($row);
//echo $name;
//echo ":-uid =";
//echo $uid;
//echo "

";

//query 2nd DB
$results1 = db_query('SELECT abhachu.mdl_user.username, abhachu.mdl_user.id FROM abhachu.mdl_user, abhachu.mdl_user_admins WHERE abhachu.mdl_user.id <> abhachu.mdl_user_admins.userid ORDER BY abhachu.mdl_user.id');

while ($row1 = mysql_fetch_array ($results1))
{
extract ($row1);
//echo $username;
//echo ":-id =";
//echo $id;
//echo "
";
if ($username == $name)
{
//echo $name;
///echo "
";
//echo $id;
//echo "
";

//Insert value into test table
//echo "INSERTING:-";
//echo $name;
$insert = "INSERT INTO abhachu.mdl_dup_admins (abhachu.mdl_dup_admins.userid) VALUE ('$id')";
$results3 = mysql_query($insert) or die(mysql_error());

//Count the number of times the ID has been put into the test table
$dupTab = "SELECT abhachu.mdl_dup_admins.userid FROM abhachu.mdl_dup_admins WHERE abhachu.mdl_dup_admins.userid = '$id'";
$rDup = mysql_query($dupTab) or die(mysql_error());
$duplicate = mysql_num_rows($rDup);
//echo "num2:-";
//echo $duplicate;
//echo "
";

//Check if the ID is already in the table
//If ID is in duplicate table the same number of times
//as the number of values in admin table, then add
if ($duplicate == $row4)
{ //echo "IM IN!!!";
$insertFull = "INSERT INTO abhachu.mdl_user_admins (abhachu.mdl_user_admins.userid) VALUE ('$id')";
$rinsertFull = mysql_query($insertFull) or die(mysql_error());
//add 1 to the number of records in the admin table
$row4 = $row4 + 1;
}
}
}

}

$dropDup = db_query('DROP TABLE abhachu.mdl_dup_admins');
//echo "dropppingDUP";

db_set_active('default');
}
}