Undefined variable: in PHP - php

Question

I'm a fairly new programmer, especially in PHP as i have come from a VB environment.
Below is the function I am having troubles with, as you can see i have had quite a few attempts (in comments). I thought id leave the comments there in case i'm closer with my other attempts.
I have never used PDO before and as you can see this function pretty much allows the user to log in.
The line if($temp == $_POST['password']) is where the problem is. Apparently $temp is undefined, but i cannot see why, i have even declared it at the top of the function to be sure. Anyone have any ideas?
public function load_user_data() {
$temp;
$sql;
try{
// $STH = dbHandler::$DBH->prepare("SELECT * FROM tblCustomer WHERE email = :email");
// $STH->bindValue(':email', $this->email);
// $STH->execute();
// $posts = $STH->fetch(PDO::FETCH_ASSOC); //If only fetch 1 line use just "fetch" instead of "fetchAll"
// echo '<pre>';
// print_r($posts);
// echo '</pre>';
//--------
$STH = dbHandler::$DBH->prepare("SELECT password FROM tblCustomer WHERE email = :email");
$STH->bindValue(':email', $_POST['usermail']);
$STH->setFetchMode(PDO::FETCH_ASSOC);
while($row = $STH->fetch()) {
$temp = $row;
}
//$temp = $STH->fetch(['password']);
// while($row = $STH->fetch()) {
// $temp = $row['password'];
// }
//--------
// $sql = "SELECT password FROM tblCustomer WHERE email = :email";
// $stmt = $PDO->query($sql);
// $row = $stmt->fetchObject();
// $temp = $row->password;
if($temp == $_POST['password']) {
$STH = dbHandler::$DBH->prepare("SELECT * FROM tblCustomer WHERE email = :email");
$STH->bindValue(':email', $this->email);
$STH->setFetchMode(PDO::FETCH_ASSOC);
echo("we have reached here");
while($row = $STH->fetch()) {
$firstname = $row['firstName'];
$lastname = $row['secondName'];
$title = $row['title'];
$companyname = $row['companyName'];
$email = $row['email'];
$phone = $row['phone'];
$email = $row['mobile'];
$startdate = $row['startDate'];
$isauthorised = $row['isAuthorised'];
$accstop = $row['accStop'];
$stopdate = $row['stopdate'];
}
}
}
catch (PDOException $e) {
print $e->getMessage();
}
}

Answer 1

The problem is here:
$STH = dbHandler::$DBH->prepare("SELECT password FROM tblCustomer WHERE email = :email");
$STH->bindValue(':email', $_POST['usermail']);
$STH->setFetchMode(PDO::FETCH_ASSOC);
while($row = $STH->fetch()) {
$temp = $row;
}
First, you need to do:
$STH->execute();
before you try to fetch rows.
Second, if the query doesn't match any rows, your while loop will never go into the body, so $temp will not be set. Since you apparently only expect to get one row from the query, you don't need to use while. Instead, do:
if ($temp = $STH->execute()) {
// all the code that depends on finding a row goes here
...
}
Inside that block, you'll need to do:
if ($temp['password'] == $_POST['password'])