Variable in an Array: True or False - php

Question

I am attempting to identify whether a variable in an array is present, and if it is state that it is "true" and if it is not state that it is "false". The problem is that I am receiveing a response for all array variables, when I only want to know if the page variable is present in the array with link like http://example.com/product.php?image_id=50
<?php
$page = $_GET['image_id'];
if (!empty($_SESSION)){
foreach($_SESSION as $name => $value2) {
if (substr($name, 0, 7)=='images_') {
$id = substr($name, 7, (strlen($name)-7));
$get = mysql_query('SELECT * FROM images WHERE image_id='.mysql_real_escape_string((int)$id));
while ($cart_info_row = mysql_fetch_assoc($get)) {
$cart = array('image_id' => $cart_info_row['image_id'],);
if (in_array($page, $cart)){echo 'true';} else {echo 'false';}
}
}
}
}
}
?>
Assuming the numbers below are in the SESSION print_r ($cart):
Array ( [image_id] => 42 ) false
Array ( [image_id] => 45 ) false
Array ( [image_id] => 50 ) true
Array ( [image_id] => 49 ) false
Now, how can I ONLY identify if variable 50 ($page = $_GET['image_id'];)is present with out the other three?

Answer 1

As I understand, your code does 2 things: 1 - checks if key images_$page exists in session and 2 - checks if image with image_id=$page exists in database.
<?php
$page = $_GET['image_id'];
if(isset($_SESSION['images_'.$page]))
{
$get = mysql_query("SELECT * FROM images WHERE image_id='".mysql_real_escape_string($page)."' LIMIT 1");
if($cart_info_row = mysql_fetch_row($get))
{
echo 'true';
}
else
{
echo 'false';
}
}
else
{
echo 'false';
}
Here isset is used to check if the key images_$page exists in $_SESSION. It is faster than making 2 calls to substr() function.
Also, since we need only checking if given image exists, foreach loop is replaced with if.
After that, a MySQL query runs, and since we need only first match, LIMIT 1 is added to make query faster. Also comparison with image_id is already included in query, so its enough to test if there are returned rows or not (that's why original while is replaced with if).