PHP - Check User Referral Page

function Login($username, $password)
	{
		try
		{
			$db = new PDO("mysql:host=".DB_HOST.";dbname=".DB_NAME.";charset=utf8", DB_USERNAME, DB_PASSWORD);
			$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
			$db->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);
		}
		catch(PDOException $ex)
		{
			echo "Unable to connect to DB";
			error_log($ex->getMessage());
		}
		
		try
		{
			$User_Info = $db->prepare("SELECT * FROM users WHERE username=:username");
			$User_Info->bindValue(":username", $username, PDO::PARAM_STR);
			$User_Info->execute();
			$Info = $User_Info->fetchAll(PDO::FETCH_ASSOC);
			
			$salt = $Info['salt'];
			
			$password = $salt . $password;
			$password = $this->CreateHash($password);
			
			$unique_key = $this->GenerateRandom();
			$unique_key = $this->CreateHash($unique_key);		
			
			$Check_User = $db->prepare("SELECT * FROM users WHERE username=:username AND password=:password");
			$Check_User->bindValue(":username", $username, PDO::PARAM_STR);
			$Check_User->bindValue(":password", $password, PDO::PARAM_STR);
			$Check_User->execute();	
			
			if($Check_User->rowCount() > 0)
			{
				while($row = $Check_User->fetchAll(PDO::FETCH_ASSOC))
				{
					session_destroy();
					session_start();
					
					$_SESSION = array();
					
					session_regenerate_id(true);
					
					$_SESSION['username'] = $row['username'];
					$session_id = session_id();
					$user_id = $row['id'];
					
					$Check_Logged_In = $db->prepare("DELETE FROM logged_in_users WHERE user_id=:userid");
					$Check_Logged_In->bindValue(":user_id", $user_id, PDO::PARAM_STR);
					$Check_Logged_In->execute();
					$has_changed = $Check_Logged_In->rowCount();
					
					if($has_changed > 0)
					{
						$Logged_In = $db->prepare("INSERT INTO logged_in_users (id, user_id, session_id, unique_key) VALUES (NULL, :user_id, :session_id, :unique_key)");
						$Logged_In->bindValue(":user_id", $user_id, PDO::PARAM_STR);
						$Logged_In->bindValue(":session_id", $session_id, PDO::PARAM_STR);
						$Logged_In->bindValue(":unique_key", $unique_key, PDO::PARAM_STR);
						$Logged_In->execute();
						$affected_rows = $Logged_In->rowCount();
						
						if($affected_rows > 0)
						{
							return true;
						}
					}
					return false;
				}
			}

			return false;
		}
		catch(PDOException $ex)
		{
			echo "Unable to complete query";
			error_log($ex->getMessage());
		}
	}

$usrsql = "SELECT * FROM $tbl_name WHERE username='$username' AND password='$password'";
        $usrres = mysql_query($usrsql);
        $usrcount = mysql_num_rows($usrres);

        if($usrres && mysql_num_rows($usrcount)>0) {

            die("Username is already taken!");
        } 

Hey, so I'm trying to check the database if the user and email already exists when registering.

<?php
include_once('includes/config.php');

if(isset($_POST['submit'])) {
	$username = $_POST['username'] ? trim($_POST['username']) : null;
	$password = md5($_POST['password']) ? trim($_POST['password']) : null;;
	$email = ($_POST['email']);
	$message = "";

	if(empty($username) || empty($password) || empty($email)) {
		$message = "All fields required";
	} else {
		$sql = "SELECT COUNT(username) AS userNum FROM users WHERE username = :username";
		$sql = "SELECT COUNT(email) AS emailNum FROM users WHERE email = :email";
		$stmt = $db->prepare($sql);

		$stmt->bindValue(':username', $username);
		$stmt->execute();

		$row = $stmt->fetch(PDO::FETCH_ASSOC);

		if($row['userNum'] >0) {
			die("That username already exists!");
		} elseif($row['emailNum'] > 0) {
			die("That email already exists!");
		}

		$sql = "INSERT INTO users (username, password, email) VALUES (:username, :password, :email)";
		$stmt = $db->prepare($sql);

		$stmt->bindValue(':username', $username);
		$stmt->bindValue(':password', $password);
		$stmt->bindValue(':email', $email);

		$result = $stmt->execute();

		if($result) {
			$message = "Registration was successful";
		}

	}
}
?>

If I remove this line "

$sql = "SELECT COUNT(email) AS emailNum FROM users WHERE email = :email";

the code works but only checks the username. How can I check both?

$inputText = 'This is testing http://www.youtube.com';

$allowedDomains = 'www.google.com
		   youtube.com/
		   http://www.test.org';

$array = preg_split('/[\s]+/', $allowedDomains);
$regex = '';//Need this line

if(preg_match($regex, $inputText)){
    print 'Domain match!';
}else{
    print 'Domain not match!';
}