MYSQLi num_rows always returns 0

Question

I am trying to use MySQLi with my website and I am writting a login script. Now i have a problem with num_rows always returning value 0

So this is my code

if($query = $mysqli->prepare("SELECT 'password','ban' FROM users WHERE 'username'=? LIMIT 1")){
            $query->bind_param('s', $username);
            $query->execute();
            $query->bind_result($db_password,$ban);                 
            $query->store_result();
            $query->fetch();
            $numrows = $query->num_rows;        

            if($numrows == 1){
                if($ban == 0)
                {
                    if($db_password == $password)
                    {
                        $_SESSION['login'] = 'ok';
                        //$_SESSION['id'] = $id;
                        //$_SESSION['realname'] = preg_replace("/[^a-zA-Z0-9_\-]+/","",$realname);
                        header("Location: /ematura/index.php");
                        $query->close();
                    }else{
                    die("Napaka");
                    }
                }else{
                    die("Račun zaklenjen");
                }
            }

My question is, why is num_rows always 0, even though the user exists?

Answer 1

列名不应使用单引号或双引号引起来，而是可以使用反引号（`）

SELECT `password`,`ban` FROM users WHERE `username`=? LIMIT 1

Answer 2

I don't think you are binding correctly, try changing to: $query->bind_param(1, $username);

From: http://php.net/manual/en/pdostatement.bindparam.php

public bool PDOStatement::bindParam ( mixed $parameter , mixed &$variable [, int $data_type = PDO::PARAM_STR [, int $length [, mixed $driver_options ]]] )

parameter

Parameter identifier. For a prepared statement using named placeholders, this will be a parameter name of the form :name. For a prepared statement using question mark placeholders, this will be the 1-indexed position of the parameter.