阻止执行php脚本，如果另一个执行它

Question

I have the following PHP code:

<?php
 $host = "localhost";
 $username = "root";
 $pw = "root";
 $db_name = "marketing";

 $Connect = mysqli_connect($host, $username, $pw) or die("Couldn't connect to+ MySQL:<0br>" . mysqli_error($Connect) . "<br>" . mysqli_errno($Connect));

 $Db = mysqli_select_db($Connect, $db_name)or die("Couldn't select database:<br>" . mysqli_error($Connect). "<br>" . mysqli_errno($Connect));

 mysqli_set_charset($Connect, "utf8");

 mysqli_autocommit($Connect,TRUE);  

 $query1 = "select status from cron_statuses where offset = 0";
 $res = mysqli_query($Connect, $query1); 
 $status = mysqli_fetch_assoc($res);

 if (!$status['status']){

    $query2 = "update cron_statuses set status = 1 where offset = 0";
    $res = mysqli_query($Connect, $query2);

    //do something
    sleep(20);

     $query2 = "update cron_statuses set status = 0 where offset = 0";
     $res = mysqli_query($Connect, $query2);
}
else{
    echo 'cron blocked';
 }     

?>

Default value for status = 0. if I run the script it will then update status to 1 and then sleep 20 secs and update the status back to 0.

Whiles sleeping, if the script is run in another tab I would expect the status to equal to 1, and should enter the echo cron_block but if its = 0 it should do the same as the first tab.

Answer 1

the issue because I run the same script in same browser (firefox) with 2 tabs.

when I run the first on firefox and the second in chrome the behaviors went as I expected.

also, when run the first with localhost/script.php and the other 192.10.1.5/script.php on same browser with different tabs the behaviors went as I expected.

I do not know why but the issue not in code.