错误：无法使用user @ host建立数据库连接

Here is how my website connected to mysql database untill php was upgraded to version 5.4

public function core() {        
  if (!@$this->dbCon = mysql_connect($this->host, $this->user,$this->password)) {
    exit('Error: Could not make a database connection using ' .
      $this->user . '@' . $this->host);
  }  

But now, I get Error: Could not make a database connectionz using user@host.
How do I rewrite this code using PDO?

mysql functions are deprecated. Try to use mysqli_connect function.