// Getting the id of the restaurant to which we are uploading the pictures
$restaurant_id = intval($_GET['restaurant-id']);

if(isset($_POST['submit']))
{
    $tmp_files = $_FILES['rest_pics']['tmp_name'];
    $target_files = $_FILES['rest_pics']['name'];
    $tmp_target = array_combine($tmp_files, $target_files);
    $upload_dir = $rest_pics_path;
foreach($tmp_target as $tmp_file => $target_file)
    {
        if(move_uploaded_file($tmp_file, $upload_dir."/".$target_file))
        {
            $sql = sprintf("
            INSERT INTO rest_pics
            (branch_id, pic_name)
            VALUES ('%s', '%s')"
            , mysql_real_escape_string($restaurant_id)
            , mysql_real_escape_string(basename($target_file)));
            $result = mysql_query($sql) or die(mysql_error());
        }

I get the next error:

Cannot add or update a child row: a foreign key constraint fails (rest_v2.rest_pics, CONSTRAINT rest_pics_ibfk_1 FOREIGN KEY (branch_id) REFERENCES rest_branches (branch_id) ON DELETE CASCADE ON UPDATE CASCADE

However, this error totally disappears and everything goes well when I put directly the restaurant id (14 for example) instead of $restaurant_id variable in the sql query.

The URL am getting the id from is: http://localhost/rest_v2/public_html/admin/add-delete-pics.php?restaurant-id=2

Any help please?