PHP选择 - 浏览器和QR码阅读器的不同价值

Question

I try to make a landing page: if somebody reads my QR code (example: some.com/qr.php?id=1), this php increments the record's value in sql. Strange thing, that when I run the php from PC's browser by typing URL, it increments my field by 1 as I wanted. But when my phone reads and then opens the QR code, it increments by 2. Do you have any idea about the problem?

$id=$_GET['id'];

$sql = "SELECT url, name
        FROM qrcode_pagelist 
        WHERE id = '$id' ";

$sourceurlidlist = mysql_query($sql, $db);

while ($row = mysql_fetch_assoc($sourceurlidlist)) { 
    $sourceurl=$row['url']; $name=$row['name']; 
}

$vandatum=0;

$counter=0;

$sql = "SELECT date,counter
        FROM qrcode_visitorcount
        WHERE name='$name'";

$datelist = mysql_query($sql, $db);
while ($sor = mysql_fetch_array($datelist))
{ 
    if (date("Y-M") == $sor['date'])
    {
        $vandatum = $vandatum+1;
        $date = $sor['date'];
        $counter = $sor['counter'];
        $counter++;
    }
}

if ($vandatum>0)
{
  $sql = "UPDATE qrcode_visitorcount
          SET counter = $counter
          WHERE date = '".$date."' AND name='$name'";
  $insert = mysql_query($sql, $db);
}
else 
{
  $sql = "INSERT INTO qrcode_visitorcount (name, date, counter) 
          VALUES ('".$name."', '".date('Y-M')."', 1)";
  $insert = mysql_query($sql, $db);
}

header('Location: '.$sourceurl);
die();

Answer 1

You might find that the phone is actually fetching the page twice. Try and use a session to check if the page was checked already, (just set a time value for example).

If the value is set, you will know that your phone is hitting the page twice.

EDIT

...
session_start();
if (!isset($_SESSION['check'])) 
{
  $_SESSION['check'] = time();

  // add all the code above
}

...