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How do I use PHP and MYSQL to fill fields with in a form when the data comes from multiple tables? [closed]
<?php
$connect = mysql_connect("localhost","*********","******") or die ("Couldn't Connect"); //host,username,password
mysql_select_db("virtua15_j*1**") or die ("Could not find database");

$query = mysql_query("SELECT * FROM jos_users LEFT JOIN jos_comprofiler ON jos_users.id=jos_comprofiler.id WHERE jos_users.id = $id");


?>
<html>
<form action="populate.php" method='post'>
 <table>
<tr>
        <td>VAE&nbsp;Username:</td>

        <td><input type='text' name='username' value=''></td>
      </tr>
      <tr>
        <td>VAE&nbsp;Password:</td>

        <td><input type='password' name='password' value=''></td>
      </tr>
 </table>
  <p><input type='submit' name='submit' value='Search & Populate!'></p>
</form>
<hr>

<form action="dafreg.php" method='post'>
<table>
<tr>
<td>Fristname:</td>
<td><input type='text' name='firstname' value='<?php echo $firstname; ?>'></td>
</tr>
<tr><td>Lastname:</td>
<td><input type='text' name='lastname' value='<?php echo $lastname; ?>'></td>
</tr>
<tr>
<td>Login:</td>
<td><input type='text' name='login' value='<?php echo $username; ?>'></td>
</tr>
<tr><td>Password:</td>
<td><input type='text' name='pass' value=''></td>
</tr>
<tr><td>Country:</td>
<td><input type='text' name='country' value=''></td>
</tr>
<tr><td>Pilot:</td>
<td><input type='checkbox' name='pilot' value=''></td>
</tr>
<tr><td>ATC:</td>
<td><input type='checkbox' name='atc' value=''></td>
</tr>
<tr><td>Email:</td>
<td><input type='text' name='email' value=''></td>
</tr>
 </table>
 <p><input type='submit' name='submit' value='Register'></p>
 </form>


</form>


</html>

$query = mysql_query("SELECT jos_users.FirstName, jos_users.LastName FROM jos_users LEFT JOIN jos_comprofiler ON jos_users.id=jos_comprofiler.id WHERE jos_users.id = " . mysql_real_escape_string($id));

if ($row = mysql_fetch_assoc($query))
{
    $firstname = $row['FirstName']; //This is whatever the field is called in your table
    $lastname = $row['LastName'];
}

$username = $_POST["username"];
$password = $_POST["password"];

$query = mysql_query("SELECT firstname, lastname, ... FROM jos_users LEFT JOIN jos_comprofiler ON jos_users.id=jos_comprofiler.id WHERE jos_users.username = " . $username);