<?php
if(!isset($_POST['submit'])){
 exit('login in error.');
}
$username = htmlspecialchars($_POST['username']);
$password = MD5($_POST['password']);
include('conn.php');
echo"$password";
$check_query = mysqli_query($result,"select USERID from USERINFO where EMAIL='$username' and PASSWORD='$password' limit 1");
if($ret = mysqli_fetch_array($check_query)){

 echo'connect true.';
}
else
{
 echo'connect false';
}
?>

UPDATE USERINFO SET PASSWORD = md5('root') WHERE USERID = 1000;

<?php
try{
$result = mysqli_connect('localhost','root','root');
mysqli_select_db($result,'WEBDATAS');
}catch(Exception $e)
{
 echo $e->message;
 exit;
}
if(!$result)
{
 return false;
}
echo "ok\n";
?>

<?php
session_start();
include_once('data.php');

$handle = db_connect();
if(!$handle){
 echo 'Did not access to the database';
}else{
 echo'connect success';
}
?>

<div class="modal fade" tabindex="-1" role="dialog" id="login">
   <div class="modal-dialog" role="document">
    <div class="modal-content">
     <div class="modal-header">
      <button type="button" class="close" data-dismiss="modal" aria-label="Close"><span aria-hidden="true">×</span></button>
      <h3 class="modal-title">ログイン</h3>
     </div>
     <div class="modal-body">
      <form class="form-signin" action="login.php" method = "post">
       <h4 class="form-signin-heading">利用者名 パスワード 入力</h4>
       <label for="inputEmail" class="sr-only">利用者名</label>
       <input type="email" name="username" id="inputEmail" class="form-control" placeholder="利用者名を入力" required autofocus>
       <label for="inputPassword" class="sr-only">パスワード</label>
       <input type="password" name="password" id="inputPassword" class="form-control" placeholder="パスワード" required>
       <div class="checkbox">
        <label>
        <input type="checkbox" value="remember-me"> ログイン状態を保持
       </label>
       </div>
       <button class="btn btn-lg btn-primary btn-block" type="submit" name="submit">ログイン</button>
      </form>
     </div>
     <div class="modal-footer">
      <button type="button" class="btn btn-default" data-dismiss="modal">クローズ</button>
     </div>
    </div>
    <!-- /.modal-content -->
   </div>
   <!-- /.modal-dialog -->
  </div>