php - Warning: mysql_fetch_assoc() expects parameter 1 to be resource, object given

I
cant seem to figure out what I'am doing wrong. So when I submit my form I get Warning
error and the

Notice: Undefined variable: dbusername in
/Library/WebServer/Documents/ArturoLuna_Final/loginCheck.php on line
30

$username
            = $_POST['username'];
$password = $_POST['password'];
            


if($username&&$password)
{

            require 'conn.php';
 $query = "SELECT * FROM users WHERE
            username='$username'";
 $result = $mysql->query($query) or
            die(mysqli_error($mysql));
 $numrows =
            $result->num_rows;

 if ($numrows!=0)
 {

            while($row = mysql_fetch_assoc($result))

 { 
 $dbusername
            = $row['username'];
 $dbpassword = $row['password']; 

            }

 //check to see if they match!

            if($username==$dbusername&&$password==$dbpassword)
 { 
 echo
            "youre In!";
 }

 else
 echo "incorrect
            password!";

 }
 else
 die("that user is
            dead");

 //echo
            $numrows;

}


else


            echo ("Please Enter
            Username")

what can I
be possibly doing wrong?