警告：PDO :: __ construct（）：php_network_getaddresses：getaddrinfo失败：此类主机未知

Question

我正在尝试使用php连接到本地数据库。

我尝试检查所有内容，它们似乎都正确，但仍然失败

这是配置设置

 <?php

 $servername = "localhost";
 $db_user ="root";
 $db_pass = "";
 $db_name = "useraccounts";

 $db = new PDO("mysql:host= $servername; db_name=  $db_name" , $db_user,     $db_pass);
 $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);    
 ?>

这是我要发布的数据

<?php
if(isset($_POST['submit'])) {
  $firstname      = $_POST['firstname'];
  $lastname       = $_POST['lastname'];
  $referrer       = $_POST['referrer'];
  $nationality    = $_POST['nationality'];
  $phone          = $_POST['phone'];
  $email          = $_POST['email'];
  $password       = $_POST['password'];

  $sql = "INSERT INTO users (firstname, lastname, referrer, nationality, phone, email, passowrd) VALUES(?,?,?,?,?,?,?)";
  $stmtinsert = $db->prepare( $sql );
  $result = $stmtinsert->execute([$firstname, $lastname, $referrer, $nationality, $phone, $email, $password]);

  if($result) {
    echo 'successfully saved.';
  } else {
    echo 'There was a problem';}
 }
 ?>

我想发布到数据库，但是出现错误