如何在表单旁边显示php表单验证错误？

Question

i have created a signup form which is validated by both javascript and php.Whenever any javascript form validation error occur such as username is required,it is displayed beside the form,But when any php validation error occur such as username already exist,it is displayed on another link.How can i display php validation errors beside the form?

<?php

 include('configdb.php');
 if(isset($_POST['submit']))
 {
 checks if the username is in use

if (!get_magic_quotes_gpc()) {

    $_POST['username'] = addslashes($_POST['username']);

}

 $usercheck = $_POST['username'];

 $sql1 = "SELECT username FROM users WHERE username = '$usercheck'"; 
 $result1 = mysqli_query($mysqli,$sql1) or die(mysqli_error());


//if the name exists it gives an error

if (mysqli_num_rows($result1) != 0) {

    die('Sorry, the username '.$_POST['username'].' is already in use.');
    }
     } 

Answer 1

Another option if you don't want to use ajax. It can be done with php but user need to reload the page to see error.

To do this, html form code and php validation code must be placed at the same file.

<?php 
    $error = false;
    if(isset($_POST['submit'])){                
        // your validation
            // if something wrong
            $error = true;  
    }
?>
<form action="validation_checking.php" method="post">
    <?php
        if($error)
        { echo '<p style="color:red;">Sorry, the username '.$_POST['username'].' is already in use.</p>'; } 
    ?>
    <input type="text" name="username"> 
    <input type="submit" value="submit">
</form>