Array not storing data from form - php

Question

I am creating a user settings page allowing members to update their information. The information displays, however once changed doesn't update on the database, although no errors are produced and the success page is displayed. I have tried echoing the array and it appears to be blank meaning it's not parsing any of the new data.
<?php
include ("storescripts/init.php");
protect_page();
if (empty($_POST) === false) {
$required_fields = array('mem_email','mem_first_name','mem_last_name');
foreach ($_POST as $key=>$value) {
if (empty($value) && in_array($key, $required_fields) == true) {
$errors[] = 'Fields marked with an asterisk are required';
break 1;
}
}
if (empty($errors) === true) {
if (filter_var($_POST['mem_email'], FILTER_VALIDATE_EMAIL) === false) {
$errors[] = 'A valid email address is required';
} else if(user_exists($_POST['mem_email']) === 1 && $member_data['mem_email'] !== $_POST['mem_email']) {
$errors[] = 'Sorry, the email \'' . htmlentities($_POST['mem_email']) . '\' is already in use';
}
}
}
if (empty($_POST) === false && empty($errors) === true) {
$update_data = array(
'mem_first_name' => $_POST['mem_first_name'],
'mem_last_name' => $_POST['mem_last_name'],
'mem_email' => $_POST['mem_email'],
'allow_email' => ($_POST['allow_email']) ? 1 : 0);
update_user($session_member_id, $update_data);
header('Location: settings.php?success=1');
die();
}
include ("includes/overall/head.php");
?>
<?php include ("includes/overall/template_header.php");?>
<div id="mainDivShort">
<h1>User Settings</h1>
<div id="divBreak"></div>
<?php include ("includes/overall/column_left.php");?>
<div id="middleContent">
<?php if (isset($_GET['success']) && isset($_GET['success'])) {
echo 'Your details have been updated';
} else {
if (empty($errors) === false) {
echo output_errors($errors);
}?>
<form action="" method="post">
<ul>
<li>First Name*: <br> <input type="text" name="mem_first_name"
value="<?php echo $member_data['mem_first_name'];?>">
</li>
<li>Last Name*: <br> <input type="text" name="mem_last_name"
value="<?php echo $member_data['mem_last_name'];?>">
</li>
<li>Email*: <br> <input type="text" name="mem_email"
value="<?php echo $member_data['mem_email'];? >">
</li>
<li>
<input type="checkbox" name="allow_email" <? php if ($member_data['allow_email'] == 1) { echo 'checked="checked"'; } ?>> Would you like to receive an email about news and promotions?
</li>
<li><input type="submit" value="Update">
</li>
</ul>
</form>
<?php }?>
</div>
<?php include ("includes/overall/column_right.php");?>
</div>
<?php include ("includes/overall/template_footer.php");?>
And my update_user function
function update_user($mem_id, $update_data) {
$update = array();
array_walk($update_data, 'array_sanitize');
foreach ($update_data as $field=>$data) {
$update[] = '`' . $field . '` = \'' . $data . '\'';
}
mysql_query("UPDATE `members` SET " . implode(', ', $update) . " WHERE `mem_id`= $mem_id");
}

Answer 1

do you receive the correct data in your update_user function ?
try this
function update_user($mem_id, $update_data) {
$update = array();
array_walk($update_data, 'array_sanitize');
foreach ($update_data as $field=>$data) {
$update[] = '`' . $field . '` = \'' . $data . '\'';
}
$sql = "UPDATE `members` SET " . implode(', ', $update) . " WHERE `mem_id`= $mem_id";
echo $sql; exit();
//mysql_query("UPDATE `members` SET " . implode(', ', $update) . " WHERE `mem_id`= $mem_id");
}
Fire this $sql output in your db to check if you have sql errors or any other db errors