Vikas Code

<!-- AJAX: -->
<script>
    $(document).ready(function(){
        $("#signupform").submit(function(event){
            event.preventDefault();
            $.ajax({
                url: "submitform.php",
                type: "POST",
                data: $('#signupform').serialize(),
                success: function(result){
                    if(result! = ""){
                        alert("Error");
                    }
                    else{
                        $(location).attr('href', 'login2.php');
                    }
                },
                error: function(){
                    alert("error");
                }
            });
            //}
        });
    });
</script>

<!-- PHP: -->

<?php
    ini_set("display_errors", 1);
    session_start();
?>
<?php
    $conn = mysqli_connect("localhost", "root", "", "winkcage");
    $im = $_SESSION["pathsession"];
    $nam = $_POST["name"];
    $usernam = $_POST["username"];
    $phon = $_POST["phone"];
    $pass = $_POST["password"];
    $userexist = "SELECT * FROM signup WHERE username = '$usernam'";
    $userexistrun = mysqli_query($conn, $userexist);
    $userResults = mysqli_num_rows($userexistrun);
    if($userResults == 1)
    {
        echo "This user already exits";
    }
    else
    {
        $signquery = "INSERT INTO signup(name, username, phone, password, img) VALUES('$nam', '$usernam', '$phon', '$pass', '$im')";
        if ($im != "" && $nam != "" && $usernam != "" && $phon != "" && $pass != "")
        {
            $signqueryrun = mysqli_query($conn, $signquery);
        }
    }
?>