Issue implementing class

[supertrucker]

Hello,I have written a custom class that is going to handle all of my CRUD operations for my "user" table. Below is the class:

<?php 	class UserDb {			const TABLE = "users";		const KEY_ID = "Id";		const KEY_EMAIL = "email";		const KEY_JOIN_DATE = "joinDate";		const KEY_VERIFIED = "verified";		const KEY_LAST_LOGIN = "lastLogin";		const KEY_FIRST_NAME = "firstName";		const KEY_LAST_NAME = "lastName";		const KEY_PASSPHRASE = "passphrase";				private $db = null;		public function __construct() {			$this->db = new PDO(					'mysql:host=' . HOST_NAME . 					';dbname=' . DATABASE_NAME . 					';charset=utf8', DATABASE_USER, DATABASE_PASS			);			$this->db->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);			$this->db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);		}			public function userExists($email) {			$sql = $this->db->prepare("SELECT * FROM " . self::TABLE . " WHERE " . self::KEY_EMAIL . " = :email");			$sql->execute(array(':email' => $email));			$row_count = $sql->rowCount();			if ($row_count > 0) { return true; }			else { return false; }		}				public function insertUser($user = null) {			if (is_null($user)) { $user = new User(); } 		}			}	?>

When I run this, I get:

Fatal error: Using $this when not in object context in /media/mypassport/var/www/jcbook/include/classes/class.UserDb.php on line 28

Can anyone tell me what I've done wrong? I've never worked with classes in php before.Thank you in advance! Edited May 3, 2013 by supertrucker

[justsomeguy]

You get that error when you run userExists? How do you run it?

[supertrucker]

Wow, I feel a little dumb now! I was calling the method with '::' instead of '->', thanks!