Johnnygirl Johnnygirl - 3 days ago 4
MySQL Question

PHP select - different value with browser and QR-code reader

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

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
}

...

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