PHP登录/会话在提交时终止

我成功地创建了一个连接到MySQL并插入新用户信息的注册表。然而，当需要登录并创建会话时，一旦我单击“提交”，一切似乎都消失了。无论我是否正确填写了任何内容，屏幕都会刷新，没有错误输出。任何帮助都将不胜感激

Register.php

带有会话的PHP登录表单
登录表单



用户名：




密码：

编辑

<input type="submit" value="Login" />

到

正如前面的人所说，您必须为输入标签命名。否则，php不知道您要做什么

我觉得很傻，谢谢你

   <?php
session_start();
include("includes/connect.php"); //Establishing connection with our database

$error = ""; //Variable for storing our errors.
if(isset($_POST["submit"]))
{
if(empty($_POST["username"]) || empty($_POST["password"]))
{
$error = "Both fields are required.";
}else
{
// Define $username and $password
$username=$_POST['username'];
$password=$_POST['password'];

// To protect from MySQL injection
$username = stripslashes($username);
$password = stripslashes($password);
$username = mysqli_real_escape_string($db, $username);
$password = mysqli_real_escape_string($db, $password);
$password = md5($password);

//Check username and password from database
$sql="SELECT id FROM users WHERE email='$username' and password='$password'";
$result=mysqli_query($db,$sql);
$row=mysqli_fetch_array($result,MYSQLI_ASSOC);

print_r($row);

//If username and password exist in our database then create a session.
//Otherwise echo error.

if(mysqli_num_rows($result) == 1)
{
$_SESSION['username'] = $login_user; // Initializing Session
header("location: home.php"); // Redirecting To Other Page
}else
{
$error = "Incorrect username or password.";
}

}
}

?>

<div class="ui container center aligned">
<h1>PHP Login Form with Session</h1>
<div class="loginBox">
<h3>Login Form</h3>
<br><br>
<form method="post" action="">
<label>Username:</label><br>
<input type="text" name="username" placeholder="username" /><br><br>
<label>Password:</label><br>
<input type="password" name="password" placeholder="password" />  <br><br>
<input type="submit" value="Login" /> 
</form>
<div class="error"><?php echo $error;?></div>
</div>
</div>

<input type="submit" value="Login" />

<input type="submit" value="Login" name="submit"/>