Untitled

Index.PHP:
          <!doctype html>
          <html lang="en">
            <head>
             <section class="main-container">
             <div class="main-wrapper">
            <form class="calendar-form" action="button.inc.php" method="POST">
            <meta charset="utf-8">
            <meta name="viewport" content="width=device-width, initial-scale=1">
        <title>jQuery UI Datepicker - Default functionality</title>
            <link rel="stylesheet"
         href="//code.jquery.com/ui/1.12.1/themes/base/jquery-
             ui.css">
       <link rel="stylesheet" href="/resources/demos/style.css">
            <script src="https://code.jquery.com/jquery-1.12.4.js"></script>
             <script src="https://code.jquery.com/ui/1.12.1/jquery-ui.js">
        </script>
           <script>
         $( function() {
              $( "#datepicker" ).datepicker();
           } );
          </script>
           </head>
       <body>

           <p>Date: <input type="text" id="datepicker"></p>
        <button type="submit" name="submit">Check Availability</button>

              </body>
               </html>


Button.inc.Php:
         <?php
          if (isset($_POST['submit'])) {

       include_once 'dbh.inc.php';

            $date = mysqli_real_escape_string($conn, $_POST['date']);


            if (empty($date)) {
              header("Location: ../calendar/index.php?index=empty");
               exit();
                 } else {


                 $sql = "INSERT INTO system (date) VALUES ('$date');";
        $result = mysqli_query($conn, $sql);
         header("Location: ../calendar/index.php?index=success");
             exit();


               }


             } else {
            header("Location: ../calendar/index.php");
             exit();
                }


       ?>


Dbh.inc.php:

      <?php


      $dbServername = "localhost";
      $dbUsername = "root";
       $dbPassword = "";
         $dbName = "calendar";

          $conn = mysqli_connect
   ($dbServername,$dbUsername,$dbPassword,$dbName);