PHP月、年、日选择下拉列表，生成中间件的日期格式

<form action="middleware.php" method="post">
  <select name="month">
    <option value="01">January</option>
    <option value="02">February</option>
    ...
    <option value="12">December</option>
  </select>
  <select name="year">
    <option value="2022">2022</option>
    <option value="2023">2023</option>
    ...
    <option value="2030">2030</option>
  </select>
  <select name="day">
    <option value="01">01</option>
    <option value="02">02</option>
    ...
    <option value="31">31</option>
  </select>
  <input type="submit" value="Submit">
</form>

<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
  $month = $_POST["month"];
  $year = $_POST["year"];
  $day = $_POST["day"];

  $middlewareDateFormat = $year . "-" . $month . "-" . $day;
  // 进一步处理中间件的日期格式，例如存储到数据库或进行其他操作

  echo "中间件日期格式：" . $middlewareDateFormat;
}
?>