<form action="includes/profile_picture_inc.php" method="POST" enctype="multipart/form-data" id="form">
   <input type="file" name="file" id="upload" onchange="document.getElementById('form').submit();">
</form>

if (isset($_POST['submit'])) {
    $target_dir = "../users/".$_SESSION['u_id']."/image/";
    $str = "1234567890qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM";
    $rand = substr(str_shuffle($str), 0, 10);
    $temp = explode(".", $_FILES["file"]["name"]);
    $newfilename = $rand . '.' . end($temp);
    $target_file = $target_dir . $newfilename;
    $uploadOk = 1;
    $imageFileType = strtolower(pathinfo($target_file,PATHINFO_EXTENSION));
    // Check if image file is a actual image or fake image
    if(isset($_POST["submit"])) {
        $check = getimagesize($_FILES["file"]["tmp_name"]);
        if($check !== false) {
            echo "File is an image - " . $check["mime"] . ". <br/>";
            $uploadOk = 1;
        } else {
            echo "File is not an image. <br/>";
            $uploadOk = 0;
        }
    }
    // Check if file already exists
    if (file_exists($target_file)) {
        echo "Sorry, file already exists. <br/>";
        $uploadOk = 0;
    }
    // Check file size
    if ($_FILES["file"]["size"] > 5000000) {
        echo "Sorry, your file is too large. <br/>";
        $uploadOk = 0;
    }
    // Allow certain file formats
    if($imageFileType != "jpg" && $imageFileType != "png" && $imageFileType != "jpeg"
    && $imageFileType != "gif" ) {
        echo "Sorry, only JPG, JPEG, PNG & GIF files are allowed. <br/>";
        $uploadOk = 0;
    }
    // Check if $uploadOk is set to 0 by an error
    if ($uploadOk == 0) {
        echo "Sorry, your file was not uploaded. <br/>";
    // if everything is ok, try to upload file
    } else {
        if (move_uploaded_file($_FILES["file"]["tmp_name"], $target_file)) {
            require 'database_inc.php';
            $sql = "UPDATE `users` SET `user_profile` = '$newfilename' WHERE 1";
            if (mysqli_query($conn,$sql)) {
                $_SESSION['profile_picture'] = $newfilename;
                header("Location: ../profile.php");
            } else {
                echo "The query has not been updated. <br/>";
            }

        } else {
            echo "Sorry, there was an error uploading your file. <br/>";
        }
    }
}

if (isset($_POST['submit'])) {

<form action="includes/profile_picture_inc.php" method="POST" enctype="multipart/form-data" id="form">
   <input type="file" name="file" id="upload" onchange="document.getElementById('form').submit();">
   <input type="hidden" name="submit" value="1" />
</form>