How to echo error if there is wrong URL? Need help

[toplisek]

I have code and it reads from URL number ID. How to report error message if $_GET['number'] is not the same as in db?

reactivationnum=$_GET['number'];


$query = "SELECT * FROM membership WHERE reactivationnum = '$reactivationnum'";
$result1 = mysql_query($query);

 while ($row = mysql_fetch_array($result1))
{       $reactivation = $row["reactivation"];      
         if ($reactivation==1 )

      {      
                echo "<script language='javascript'>
                    document.location='activated.php';</script>";  }

       else
        {
                 echo "<script language='javascript'>
                    document.location='notactivated.php';</script>";     
         }
 } 

[thetestingsite]

If you're trying to do what I think you're doing, try the following:

<?php

$reactivationnum=$_GET['number'];


$query = "SELECT * FROM membership WHERE reactivationnum = '$reactivationnum'";
$result1 = mysql_query($query);

if (!mysql_num_rows($result1)) {

        echo "<script language='javascript'>
                    document.location='notactivated.php';</script>"; 
}

else {

        echo "<script language='javascript'>
                    document.location='activated.php';</script>"; 
}

?>

That will check the database for any matching rows for $reactivationnum. If it does not have any matching rows, it redirects to notactivated.php. If it does have a matching row, it redirects to activated.php. Let me know if this is what you're talking about.