php - Mysqli oop method call -

i'm new implementing oop using mysqli things, have object(class) named database, real problem how call select method in index.php , how can use it

database class.php below:

class database{ private $host = null; private $user = null; private $pass = null; private $db = null; public $error = "error po sir!"; public $con;   public function connect($host, $user, $pass, $db){      $this->host = $host;     $this->user = $user;     $this->pass = $pass;     $this->db = $db;      $this->con = mysqli_connect($this->host, $this->user, $this->pass);         if(mysqli_connect_errno()){             echo "connection failed %s\n!", mysqli_connect_error();             exit();         }  }  public function select($condition){     $query = "select os_user users os_user = {$condition}";     $result = mysqli_query($this->con,$query);     return $result; } }  

this how did implement it:

    require 'templates/dbclass.php';  $db = new database(); $db->connect("localhost", "root", "", "os_db"); $username = $_post['username']; if($result = $db->select($username)){     echo $username;     if($result->num_rows > 0){         while($row = $result->fetch_object()){             echo $row->os_id;         }     } } 

but not show results. when var_dump($result) bool(false).

i've enabled error reporting, there no errors displayed.

there 3 issues select function

• is vulnerable sql injection
• it no error checking
• it useless

here how have be

public function query($sql, $bind) {     $db = $this->con;     $stm = $db->prepare($sql) or trigger_error($db->error." [$sql]");     $types = str_repeat("s", count($values));     array_unshift($bind, $types);     call_user_func_array(array($stm, 'bind_param'), $bind);     $stm->execute() or trigger_error($db->error." [$sql]");     $stm->store_result();     return $stm->get_result(); } 

used this

$sql = "select os_user users os_user = ?"; $res = $db->select($sql, $_post['username'])); while($row = $result->fetch_object()){     echo $row->os_id; }