密码被散列后，php中的登录错误

Question

我想在php中创建多个用户登录，我认为我的代码中有一些错误。

我曾尝试删除哈希密码之类的安全措施及其工作原理。但是当我再次放回它时，它说它看不到数据库中的用户和密码。

<?php
// Initialize the session
session_start();

// Include config file
require_once "config.php";


// Define variables and initialize with empty values
$username = $password = "";
$alertError = $alertMessage = $username_err = $password_err = $hashed_password = "";

// Processing form data when form is submitted
if($_SERVER["REQUEST_METHOD"] == "POST"){

  $username = test_input($_POST['username']);
  $password = test_input($_POST['password']);
  $hashed_password = password_hash($_POST['password'],PASSWORD_DEFAULT);

  // Validate username and password
  if(empty($username)){
      $username_err = "Please enter username.";
  }
  if(empty($hashed_password)){
      $password_err = "Please enter password.";
  }

if(password_verify($_POST['password'], $hashed_password )){

  //Query
  $query="SELECT username, password FROM users WHERE username='$username' AND password='$hashed_password'";

  $result = mysqli_query($link, $query) or die(mysqli_error($link));

if($result){

  $rows = mysqli_fetch_array($result);

  //Direct pages with different user levels
  if ($rows['usertype'] == "Administrator") {

    session_start();
    // Store data in session variables
    $_SESSION["loggedin"] = true;
    $_SESSION["username"] = $username;
    $_SESSION["usertype"] = $rows;
    header('location: ../myHome-IMS/index.php');
    exit;
  }
  else
  if ($rows['usertype'] == "Guest") {
    session_start();
    // Store data in session variables
    $_SESSION["loggedin"] = true;
    $_SESSION["username"] = $username;
    $_SESSION["usertype"] = $rows;
    header('location: ../myHome-IMS/guest.php');
    exit;

  }

  else
  {
    // Display an error message
    $alertError = "No account found with that username or password.";
  }

  // Close connection
  mysqli_close($link);
}
}


}

function test_input($data) {
    $data = trim($data);
    $data = stripslashes($data);
    $data = htmlspecialchars($data);
    return $data;
}
?>

我希望有多个用户以安全的方式登录。