How to redirect

[bytM3]

Will you tell what I'm doing wrong. It goes straight to "expiredpage.html" even though the value
of "expiry" is more than 0. I keep studying redirection and variable definition but nothing works. It does
update.

<?php
$link = mysqli_connect("localhost", "root", "", "prerentdb"); 
// Check connection
if($link === false){ die("ERROR: Could not connect. " . mysqli_connect_error()); }
 
$id='id';
$expiry='expiry';
 
$sql = "UPDATE numbers SET expiry=$expiry- 1 where id=$id";
if(mysqli_query($link, $sql)){ echo "expiry was updated successfully."; } 
else { echo "ERROR: Could not able to execute $sql. " . mysqli_error($link); }
 
if ($expiry == 0) { 
header("location:expiredpage.html");
// window.location.href = 'expiredpage.html';
// $(location).attr('href', 'expiredpage.html')
 } 
 
else  { 
 header("location:sysnav.html");
//window.location.href = 'sysnav.html';
//  $(location).attr('href', 'sysnav.html')
 } 
// Close connection
mysqli_close($link);
?>

[dev7060]

bytM3
Will you tell what I'm doing wrong. It goes straight to "expiredpage.html" even though the value
of "expiry" is more than 0. I keep studying redirection and variable definition but nothing works. It does
update.

Src https://wiki.php.net/rfc/string_to_n...n#introduction

Comparisons between strings and numbers using == and other non-strict comparison operators currently work by casting the string to a number, and subsequently performing a comparison on integers or floats. This results in many surprising comparison results, the most notable of which is that 0 == "foobar" returns true. This RFC proposes to make non-strict comparisons more useful and less error prone, by using a number comparison only if the string is actually numeric. Otherwise the number is converted into a string, and a string comparison is performed.