Mysqli PHP 致命错误：在非对象上调用成员函数 bind_param()

Question

我正在为某人开发仪表板，但我遇到了错误。我正在创建一个注册页面，它的作用是查看用户是否已经在数据库中，如果是，则允许他们完成注册，但是当我提交时，它会创建此错误Fatal error: Call to a member function bind_param() on a non-object on line 8

这是 PHP 代码：

<?php
include"core/config.php";

if(isset($_POST['submit']))
{
  $username = $_POST['username'];
  $email = $_POST['email'];

  $check = $db->prepare("SELECT * FROM users WHERE username = :username");
  $check->bind_param(":username",$username);
  $check->execute();
  echo $check->error;

  $emailCheck = null;
  $usernameCheck = null;
  while($row = $check->fetch())
  {
    $emailCheck = $row['email'];
    $usernameCheck = $row['username'];
  }
  if(!$email == $emailCheck)
  {
    echo 'Email doesn\'t exist!';
  }else{

    if(!$username == $usernameCheck)
    {
      echo 'Username doesn\'t exist!';
    } else
    {
      $query = $db->prepare("SELECT * FROM users WHERE username = :username AND email = :email");
      $query->bind_param(":username", $username);
      $query->bind_param(":email", $email);
      $query->execute();
       $_SESSION['username'] = $username;
      echo 'You have logged in, you will be redirected.';
      echo '<META HTTP-EQUIV="REFRESH" CONTENT="5;URL=page to set password.">';
    }
  }
}
?>

表格代码：

<form class="no-margin" method="post">
                <fieldset>
                    <div class="form-group no-margin">
                        <label for="username" >Username</label>

                        <div class="input-group input-group-lg">
                                <span class="input-group-addon">

                                </span>
                            <input id="username" type="username" name="username" class="form-control input-lg" placeholder="Username">
                        </div>

                    </div>

                    <div class="form-group">
                        <label for="Email" >Email</label>

                        <div class="input-group input-group-lg">
                                <span class="input-group-addon">

                                </span>
                            <input id="email" type="email" name="email" class="form-control input-lg"
                                   placeholder="Email">
                        </div>

                    </div>
                </fieldset>
                <div class="form-actions">
                    <button type="submit" name="submit" class="btn btn-block btn-lg btn-danger">
                        </span>
                        <small>Submit</small>
                    </button>
                    <div class="forgot"><a href="not important">Not a member? Join here!</a></div>
                </div>
            </form>

Answer 1

我假设您使用的是 ext/mysqli，因为 bind_param() 是该扩展的一部分。

Mysqli 不支持命名参数。您必须将位置参数与 ? 占位符一起使用。

Mysqli 的bind_param() 的用法也与您使用它的方式不同。您必须绑定所有参数，第一个参数是“控制”参数。我建议您阅读documentation 中的示例。

PDO 支持命名参数，每次调用可以绑定一个参数到bindParam()。

Answer 2

总是在 mysqli 连接之前有这一行

mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);