Display error message on same page if all fields not filled out?

programming
1

I am trying to change my script to show the error message on the same page, above the form instead of on another page, that I current have coded. The thing is I do not know how to do that.

Can someone help me out by showing how to do it?

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
 <head>
  <title>Website Installation</title>
  <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
  <link href="installer-styles.css" rel="stylesheet" type="text/css" />
 </head>
 <body>
  <div id="container">

  <div id="header">
   <a href="installer.php">
   Website Installation</a>
   </div>
    <div id="main">
    <div class="pad25">



<?php
if(isset($_POST['submit'])) {

if ($_POST['nextstep']=="checkuser") { //start function for the checkuser stage
if(empty($_POST['db_name']) || empty($_POST['db_user']) || empty($_POST['db_pass']) || empty($_POST['db_host']) ) { 

echo "form not fully filled, reshow first form";
}
else {
?>

<HTML>
<HEAD><title>Using PHP_SELF</title></HEAD>
<BODY> 
<FORM method="post" action="<?php echo $_SERVER['PHP_SELF']; ?>">
second form<br>
   <input type="text" name="user3"><br>
   <input type="text" name="user4"><br>
   <input type="hidden" name="nextstep" value="checkanswer">
   <input type="submit" name="submit" value="Submit Form"><br>
</FORM>
</BODY>
</HTML>

<?php
} //end function for the checkuser stage
?>

<?php
 }         
if ($_POST['nextstep']=="checkanswer") { //start function for the checkanswer stage
if(empty($_POST['user3']) || empty($_POST['user4']) ) {
 
echo "form not fully filled, reshow first second";
}
else {
?>

complete

<?php
} //start function for the checkuser stage
?>

 
<?php
} 
}
else {
?>
  



<h1>Step 1: Database Information</h1><br />
<form method="post" action="<?php echo $_SERVER['PHP_SELF']; ?>" name="form">

  <p>Enter your database connection settings. These settings will be inserted into <code>inc/config.inc.php</code> and will be used by the application.</p>
  <table style="width: 100%;">
    <tr>
      <th class="col1">Database Name</th>
      <td class="col2"><input name="db_name" type="text" size="20" /></td>
      <td class="col3">The name of the database to use.</td>

    </tr>
    <tr>
      <th class="col1">Username</th>
      <td class="col2"><input name="db_user" type="text" size="20" /></td>
      <td class="col3">Your MySQL username.</td>
    </tr>
    <tr>
      <th class="col1">Password</th>

      <td class="col2"><input name="db_pass" type="password" size="20" /></td>
      <td class="col3">Your MySQL password.</td>
    </tr>
    <tr>
      <th class="col1">Database Host</th>
      <td class="col2"><input name="db_host" type="text" size="20" value="localhost" /></td>
      <td class="col3">Most likely won't need to change this value.</td>
    </tr>
  </table><br />
   <input type="hidden" name="nextstep" value="checkuser">
   <input type="submit" name="submit" class="button" style="float:right;" value="Submit Form ›"><br>
</form>






<?php
}
?>

     </div>
    </div>
 <br class="clr" />
  </div>

 <br class="clr" />
   <div id="footer">
    <div class="footer_inner">
&copy; 2010 | Bucket
    </div>
   </div>

 </body>
</html>

I currently have the else message echoing on another page.