never ending loop : fatal error - php

Question

my code-
function create_id()
{
//global $myusername;
$part1 = substr("Piyush", 0, -4);
$part2 = rand (99,99999);
$part3 = date("s");
return $part1.$part2.$part3;
}
echo create_id(); //this is printing fine.
function isUniqueUserID($userIDToCheck)
{
$sqlcheck = "Select * FROM ruser WHERE userId='$userIDToCheck';";
$resource = mysql_query($sqlcheck)or die(mysql_error());
$count = mysql_fetch_assoc($resource);
if( count($count) > 0)
{return false;}
return true;
}
$userIDVerifiedUnique = false;
while(! $userIDVerifiedUnique )
{
$userIDToCheck = create_id();
$userIDVerifiedUnique = isUniqueUserID($userIDToCheck );
}
loop is just going on and on from while loop to function IsUniqueUser() and vice versa.????

Answer 1

If there are no rows returned from the MySQL query (i.e. the $userIDToCheck is not in the table, it is unique) then mysql_fetch_assoc will return FALSE. When that happens, count(FALSE) returns 1 (one)! Since that value is greater than zero the function returns FALSE.
In short, if there is a row returned (the string is not unique) your isUniqueUserID function returns FALSE; if there is no row returned (the string is unique) it still returns FALSE.
A simple, new, function to check on the database table could look something like the following...
function isUniqueUserID($userIDToCheck)
{
$userIDToCheck = mysql_real_escape_string($userIDToCheck); // Assume not already escaped
$sqlcheck = "SELECT 1 FROM ruser WHERE userId='$userIDToCheck' LIMIT 1";
$resource = mysql_query($sqlcheck) or die(mysql_error());
return (bool) mysql_num_rows($resource);
}

Answer 2

First, try changing your isUniqueUserID() function to this
function isUniqueUserID($userIDToCheck)
{
$userIDToCheck = mysql_real_escape_string($userIDToCheck); //prevent SQL injection
$sqlcheck = "Select userId FROM ruser WHERE userId='$userIDToCheck';";
$resource = mysql_query($sqlcheck)or die(mysql_error());
$count = mysql_num_rows($resource);
return ($count > 0) ? false : true;
There's no point in returning an associative array just to count the number of rows in it. And there's no point in doing a SELECT * when counting just do SELECT userId since that's all you're concerned with.
I don't see any other reason that isUniqueUserID() would return false unless your ruser table has every possible ID.