php - 使用 PHP POST 从 MYSQL 下载 CSV 文件

Question

我无法创建脚本来下载 CSV 文件。每次我运行脚本都会中断。我没有收到任何错误。一旦到达脚本，页面就会停止加载。我环顾四周并找到了一些答案，但似乎没有一个有效。我是 php 新手，如果您知道这里发生了什么，我将非常感谢您的解释。提前致谢!

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

$list = null;
include 'classes/Credentials.php';

try     
 {
 // Include globals from credentials.
 global $dbname, $host, $user, $pass;

// Set up on database switch
$conn = new PDO("mysql:dbname=$dbname;host=$host", $user, $pass);
$conn->exec("SET CHARACTER SET utf8");


        } catch(PDOException $e) {
            echo $e->getMessage();
                                }

 // Define and perform the SQL SELECT query
  $sql = 'SELECT * FROM rental';
  $result = $conn->query($sql);

 // If the SQL query is succesfully performed ($result not false)
  if($result !== false) 
  {
    $num_fields = mysql_num_fields($result);
    $headers = array();

    for ($i = 0; $i < $num_fields; $i++) {
    $headers[] = mysql_field_name($result , $i);             
    $fp = fopen('php://output', 'w');

    if ($fp && $result) {
        header('Content-Type: text/csv');
        header('Content-Disposition: attachment; filename="export.csv"');
        header('Pragma: no-cache');
        header('Expires: 0');
        fputcsv($fp, $headers);

        while ($row = $result->fetch_array(MYSQLI_NUM)) {
        fputcsv($fp, array_values($row));
        }

        $conn = null;        // Disconnect
        die;
    }
   }
 }
}

Answer 1

尝试

// If the SQL query is succesfully performed ($result not false)
if($result != false) {

您使用的比较运算符正在检查“不相同”和“不等于”