首先，只有当您的登录详细信息正确并且与数据库中的一行匹配时，该代码才会运行
第二，请更新此代码 'select email, password from user where email = :email and password = :password' 到 "SELECT email, password FROM user WHERE email = '$email' and password = '$password'" 最后， header('Location: index.php'); 我希望这能奏效。。。
干得好。。。

<?php  
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    // Connection Query
    $db = new Database();
    // Fetch Login Data
    $email = $_POST['email'];
    $pass = $_POST['password'];
    // Login Query
    $login = "SELECT email, password FROM user WHERE email='$email' and password='$pass'";
    // Query SQL
    $req = mysqli_query($db, $login);
    // Check if Row matched is Above Zero
    if (mysqli_num_rows($req) > 0) {
        // Redirect User
        header("Location: index.php");
    }
}
?>

更换管路

<form method="post" action="" class="form-horizontal">

具有

<form method="post" action="#" class="form-horizontal">

或者

<form method="post" action="yourfilename.php" class="form-horizontal">

或

<form method="post" action="<?php echo $_SERVER['PHP_SELF']; ?>" class="form-horizontal">

假设下面的php文件名为my\u file.php

if(isset($_POST['submit'])){

    $email = $_POST['email'];
    $pass = $_POST['password'];

    $db = new Database();
    $db->query('SELECT email, password FROM user WHERE email='$email' AND  password ='$pass');
    $db->bind(':email', $email);
    $db->bind(':password', $pass);
    $db->resultset();
    print_r($db->resultset());

    if($db->rowCount() == 1){

        header('location: index.php');  
    }

}   
?>

实际上，当您按submit时并没有调用它，所以在实际操作中，您必须指定以这种形式运行哪个php文件

<form method="post" action="my_file.php" class="form-horizontal">

          <div class="form-group">
              <h2 style="font-size: 25px; text-align: center; font-weight: 600; margin-bottom: 30px;">LOGIN HERE</h2>
          </div>
          <div class="form-group">                  
          </div>
          <div class="form-group">
              <label for="email">Email: </label>
              <input type="email" class="form-control" id="email" name="email" required="require" placeholder="Enter email">   
          </div>
          <div class="form-group">
              <label for="password">Password</label>
              <input type="password" class="form-control" id="password" name="password" required="require" placeholder="Enter password">  
          </div>           

          <input type="submit" class="btn btn-primary" name="submit" value="Login"/>
  </form>