我无法执行此PHP代码（HTML）

Question

所以我在前一段时间使用过这个，但现在当我用它与一些不同的代码（Extras）时。当我点击“登录”按钮时，似乎无法运行PHP代码。

任何人有任何想法出现问题的地方？

<?php 
    require('process.php'); //Remember $username and $password taken as variables 
    $ok = 0; //Assume nothing is ok, collect evidence to prove otherwise 

    if(isset($_POST["submit"])) { 
     //Submit clicked, user possibly logged in - check 
     $who = $_POST['nick']; 
     $pw = $_POST['pass']; 
     $verify = 'select * from users where user ="' . $who . '"'; 

     $answertable = mysql_query($verify, $connection); 
     if (!$answertable) { 
      echo 'Invalid username or password'; 
     } else { 
      list($usr, $pwd) = mysql_fetch_row($answertable); 
      if (MD5($pw) == $pwd) { 
       $ok = 1; //Valid user and password, It's A OK 

       echo 'Welcome ' . $usr; 
       //Do stuff here because you are a valid user 
       echo '<br><a href = "login.php">Logout</a>'; 

       } else { 
        echo 'Invalid username or password, please try again<br><br>'; 
       } 
      } 
    } 

    if (!$ok) { //Either login was wrong or not yet tried 
     ?>  <!-- Present from to gather login details --> 
     <div id="dialog" style="width: 350px; background-color: #FFFFFF; margin: 50px auto; border-radius: 15px; padding: 5px 15px 5px 15px;"> 
      <form role="form"> 
       <div class="form-group"> 
        <h2><center>Webmaster login</center></h2> 
       </div> 
       <div class="form-group"> 
        <p>Enter your username:</p> 
        <input id="nick" class="form-control" placeholder="Username"/> 
       </div> 
       <div class="form-group"> 
        <p>Enter your password:</p> 
        <input id="pass" class="form-control" type="password" placeholder="Password"/> 
       </div> 
      </form> 
      <hr/> 
      <div class="form-group"> 
       <form method="post" action="index.php"> 
        <button type="submit" id="loginbtn" class="btn btn-play btn-primary">Login</button> 
       </form> 
      </div> 
      <br clear="both"/> 
      <hr/> 
     </div> 
     <?php 
     } 
     ?> 

Process.php

<?php 
/* Set the connections to the database */ 
$host = 'localhost'; 
$username = 'root'; 
$password = ''; 
$dbname = 'login'; 

/* Build a bridge to the server */ 
$connection = mysql_connect($host, $username, $password) or die('Problems connecting'); 

/* Connect to the database through the bridge */ 
mysql_select_db($dbname) or die('Problems finding the database'); 

?> 

Answer 1

只能使用一种形式 -

 <div id="dialog" style="width: 350px; background-color: #FFFFFF; margin: 50px auto; border-radius: 15px; padding: 5px 15px 5px 15px;"> 
     <form role="form"> 
      <div class="form-group"> 
       <h2><center>Webmaster login</center></h2> 
      </div> 
      <div class="form-group"> 
       <p>Enter your username:</p> 
       <input id="nick" class="form-control" placeholder="Username"/> 
      </div> 
      <div class="form-group"> 
       <p>Enter your password:</p> 
       <input id="pass" class="form-control" type="password" placeholder="Password"/> 
      </div> 
     <hr/> 
     <div class="form-group"> 
       <button type="submit" id="loginbtn" class="btn btn-play btn-primary">Login</button> 
     </div> 
     <br clear="both"/> 
     <hr/> 
     </form> 
    </div> 

并添加名称提交按钮 -

<button type="submit" id="loginbtn" class="btn btn-play btn-primary" name="submit">Login</button>