带有PDO语句的数据库连接类

I've just started to learn OOP PHP and i'm trying create class that will do connection to my data base.

The code:

  class DB_CONNECT
    {
    private $host ;
    private $dbName ;
    private $userName ;
    private $password;
    private $db;

    public function __construct($host,$dbName,$userName,$password){

        $this->host = $host;
        $this->dbName = $dbName;
        $this->userName = $userName;
        $this->password = $password;

        try {

             $this->db = new PDO('mysql:host='.$this->host.';dbname='.$this->dbName.';charset=utf8',$this->userName,$this->password);
             $this->db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
             return $this->db;
        } catch (Exception $e) {

            ECHO $e->getMessage();
        }

    }   

}

 $db = new DB_CONNECT("localhost", "oopcms","viktor","viktor");


 function select($db){

    $query = $db->prepare("SELECT * FROM `test`");
    $query->execute();
    $row = $query->fetchAll(PDO::FETCH_ASSOC);
    return $row;
 }

 $x = select($db);
 var_dump($x);

But I am getting this error:

 Fatal error: Call to undefined method DB_CONNECT::prepare();

What I understand is that the PDO object couldn't be created. Can you give some guidance please?

Learning OOP is not the reason for creating pointless classes.
Unfortunately, you created one. PDO don't need a class to be built on top of it. Just leave it as is.

So, instead of

$db = new DB_CONNECT("localhost", "oopcms","viktor","viktor");

make it

$db = new PDO("localhost", "oopcms","viktor","viktor");
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

that would be way clearer and useful

who interested here is the solution of this and Pekka and Your Common Sense thank you for a tip:)

 class Select
{
       private $query;
       private $dbh;
       private $row;

public function __construct(){

    $this->dbh =  new DB_CONNECT("localhost", "oopcms","viktor","viktor");



}


public function select(){

    $this->query = $this->dbh->db->prepare("SELECT * FROM `test`");
    $this->query->execute();
    $this->row = $this->query->fetchAll(PDO::FETCH_ASSOC);
    return $this->row;
  }


}

  $sel = new Select();
   $s = $sel->select();
  var_dump($s);