somethings wrong with the mysql_num_rows(

[OranniS]

hi
i was making a start page, where one must register a personal code, as in password, to proceed to the main site.

to check if the code has already been used by someone else, i used the mysql_num_rows() function, but somethings making it fail...

this is where i define a function wich is causing the whole jam. ive tried echoeing here and there, turns out the line with the error is the one with the
$count = mysql_num_rows($result) or die(mysql_error());...


[code]PHP Code:
<?php
    session_start();
    require_once('vars.php');
   
    //connectie maken met DB
            $db = mysql_connect("localhost", "dieetopmaat_be", "dieetDB") or die(mysql_error());
            mysql_select_db(dieetopmaat_be, $db) or die(mysql_error());
   
    function check_presence($table, $row, $value){
   
        $sql = "SELECT *    FROM $table
                            WHERE $row = '$value'";
        $result = mysql_query($sql) or die(mysql_error());

        $count = mysql_num_rows($result) or die(mysql_error());

    if($count >= 1)
        {
        return TRUE;
    }else
        {
        return FALSE;
    }[/code]


thanks to anyone who replies!
OranniS

ps: dont mind the language, its written in dutch

[alpine]

[code]
<?php

function check_presence($table, $row, $value){
$sql = mysql_query("SELECT * FROM $table WHERE $row = '$value'") or die(mysql_error());
if(mysql_num_rows($sql)=="0")
{
return false;
}
else
{
return true;
}
}

?>
[/code]

[fenway]

To elaborate, 0 is a valid result, but will return false when used as a numerical comparison.