php - 变量转储不显示

Question

我试图显示 Var Dump，但我得到的只是白屏。有什么建议吗？

<?php
require('includes/config.inc.php');
require(MYSQL);
$aid = FALSE;
if (isset($_GET['aid']) && filter_var($_GET['aid'], FILTER_VALIDATE_INT, array('min_range' => 0))){
  $aid = $_GET['aid'];

  $q = "SELECT aircraft_id, aircraft_name AS name, aircraft_type AS type, tail_number AS tn FROM aircraft WHERE aircraft_id=$aid";
var_dump($q); die();
}

Answer 1

除非 MYSQL 是脚本中定义的常量，否则这行代码将失败并且脚本执行将立即停止:

require(MYSQL);

如 documentation 中所述:

require is identical to include except upon failure it will also produce a fatal E_COMPILE_ERROR level error. In other words, it will halt the script whereas include only emits a warning (E_WARNING) which allows the script to continue.