Php没有从数据库获取任何信息

Question

为什么在，txt文件（我正在使用测试邮件服务器工具）显示行SELECT mail FROM check_out而不是邮件地址？示例在照片中

编辑代码（仍然没有工作）：

<?php
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "database";


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

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

$sql = "SELECT mail FROM check_out";
$to = "SELECT mail FROM check_out";

mail($to , "ORDER", "Your order is placed !","From: vape@v.com");
$_SESSION['message'] = "Order placed succesfuly"; 
header('location:index.php');

if  (isset($_GET['up'])) {
$orderid = $_GET['up'];
mysqli_query($db, "DELETE FROM check_out WHERE id=$orderid");
header('location:index.php');
}



$conn->close();
?>

感谢您的帮助

How email address is displayed

Answer 1

我并不完全了解此脚本的用途，但我尝试修复它。 也许这会有所帮助：

{{1}}