php sql插入空白值

Question

每当我提交我的php表单时，数据在数据库中显示为空白。什么不起作用？我尝试将代码设置为不同，但无论我做什么，这些值最终都是空白的。

$conn = new mysqli($servername, $username, $password, $dbname);

if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

if (isset($_POST["email"]))
{
    $login = $_POST["email"];
} 
else 
{
    $login = null;
}

if (isset($_POST["psw"]))
{
    $psw = $_POST["psw"];
} 
else 
{
    $psw = null;
}

$login2 = mysqli_real_escape_string($conn, $login);
$psw2 = mysqli_real_escape_string($conn, $psw);  



$verify = "INSERT INTO test (email, password) VALUES ('$login2', '$psw2')";
$verify2 = mysqli_query($conn, $verify);


$conn->close();  
?>