Fejl I mysql query

Hej Eksperter. Jeg er ved at lave et login system, dog får jeg en mysql fejl. Jeg tror fejlen ligger i min "dobbelt WHERE" (Jeg er umiddelbart nybegynder til oop)

Hvordan kan jeg lave dette korrekt?


Invalid query: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '= AND = d41d8cd98f00b204e9800998ecf8427e' at line

$dbconnect = new DB_Class('database', 'username', 'password');

if(isset($_POST["global_user"]) && isset($_POST["global_pass"])) {  //trying to catch posts

$userquery = "SELECT id,username,password,sirname FROM table WHERE $username = ".strtolower($_POST[global_user])." AND $password = ".md5(strtolower($_POST[global_pass]))."";

$result = $dbconnect->getone($userquery);
       
if($result) {  //if correct information: perform login
           
        $user = $dbconnect->fetch($userquery); // do stuff








<?
class DB_Class
{

var $db;

function DB_Class($dbname, $username, $password)
{
  $this->db = mysql_connect ('localhost', $username, $password)
    or die ("Unable to connect to Database Server");

  mysql_select_db ($dbname, $this->db)
    or die ("Could not select database");
}

function query($sql)
{
  $result = mysql_query ($sql, $this->db)
    or die ("Invalid query: " . mysql_error());
  return $result;
}

function fetch($sql)
{
  $data = array();
  $result = $this->query($sql);
  while($row = mysql_fetch_assoc($result)) {
    $data[] = $row;
  }
  return $data;
}

function getone($sql)
{
  $result = $this->query($sql);
  if(mysql_num_rows($result) == 0)
    $value = FALSE;
  else
    $value = mysql_result($result, 0);
  return $value;
}

}
?>


På forhånd tak!