Declaring new class() beginning of class - php

Question

I'm working on a Content Management System for My wife who wants to create a website, and I have a way I've always done things within the past, but I want to deliver better coding procedures, so this is my dilemma.
This is Code I've used in the past that I know works.
class accounts {
public function CheckAccountLogin() {
global $db;
$query = <<<SQL
SELECT id,gaToken
FROM accounts
WHERE password_hash = :hashedpw
SQL;
$resource = $db->sitedb->prepare( $query );
try {
$resource->execute( array (
':hashedpw' => sha1($_POST['user-name'].':'.$_POST['user-pass']),
));
if($resource->rowCount() == 0 ) { echo false;}
else {
foreach($resource as $row) {
$this->authkey = $row['gaToken'];
if($this->authkey == "") {
self::SetSession();
}
else {
self::CheckAuth();
}
}
}
catch(PDOException $e) {
echo $e->getMessage();
}
}
}
Now every function would need global $db at the start of the function in order to utilize $db->sitedb or else we would have an error thrown our way, so what I want to do instead is
class accounts {
public $db = new db();
public function CheckAccountLogin() {
$query = <<<SQL
SELECT id,gaToken
FROM accounts
WHERE password_hash = :hashedpw
SQL;
$resource = $this->sitedb->prepare( $query );
try {
$resource->execute( array (
':hashedpw' => sha1($_POST['user-name'].':'.$_POST['user-pass']),
));
if($resource->rowCount() == 0 ) { echo false;}
else {
foreach($resource as $row) {
$this->authkey = $row['gaToken'];
if($this->authkey == "") {
self::SetSession();
}
else {
self::CheckAuth();
}
}
}
catch(PDOException $e) {
echo $e->getMessage();
}
}
}
This way within all my new functions I'm able to simply declare $this->sitedb whenever I need to connect to the database. With the above code I'm given
Parse error: syntax error, unexpected 'new' (T_NEW) in /var/www/html/functions.d/accounts.class.php on line 3. I know where the issue is, I'm just looking for a cleaner way than my first code block. Any help in getting this to work correctly would be greatly appreciated.

Answer 1

You can't initialize a variable there unless it can be evaluated at compile time. So you can't call new there. See the docs. Do it in the constructor.
class accounts {
public $db;
public function __construct() {
$this->db = new db();
}
}

Answer 2

You can create a global class DbConnect where you statically define the database object db and connect it to your database, in this way you will keep a single database connection object throughout your application.
Include this class at the beginning before any code, then you can access this object anywhere through :: operator in any class that follows.