如何在刷新页面时停止“Conform form resubmission”对话框

Question

I am using an subscribe script to add the user email address to mysql record. I used the below code for this process .It works fine .after user submit the email the page is refreshed and database is also updated to mysql :-) . But the issue is ,When i refresh the page after submitting the email ,i'm getting an conform form resubmission dialog .If i click continue button the same email (dublicate) is updating in new record.my db is updating with same email address when the i refresh page. How to disable this message and stop updating the same duplicate records in mysql.

<form id="myForm" action="" onsubmit="return validateForm();"method="post">
    <input type="hidden" name="action" value="update" />
    <input type="text" name="email" id="email" value="Enter your email here" onfocus="if (this.value == 'Enter your email here') {this.value = '';}" onblur="if   (this.value == '') {this.value = 'Enter your email here';}" onwebkitspeechchange = "this.value = this.value.replace('Enter your email here','')" style=" margin:0px 0px 0px 26px;color:#999; border:4px solid #bbb;border-radius:6px;font-size:1em;width:260px;height:30px; font-style:italic; font-family:"Times New  Roman", Times, serif;"/>
    <br>
    <center>
        <input class="button" type="image" src="rss.png" />
    </center>
</form>
<?php
    $email = $_POST['email'];
    mysql_connect ("localhost", "root", "") or die ('Error: ' . mysql_error());
    mysql_select_db ("test"); 
    $query="INSERT INTO newsletter_emails (email)VALUES ('".$email."')";
    mysql_query($query) or die ('Error updating database');
?>
<script>
function validateForm() {
    var x = document.forms["myForm"]["email"].value;
    var atpos = x.indexOf("@");
    var dotpos = x.lastIndexOf(".");
    if (atpos < 1 || dotpos < atpos + 2 || dotpos + 2 >= x.length) {
        alert("Not a valid e-mail address");
        return false;
    } else {
        alert("thankyou");
    }
}
</script>

Answer 1

When you submit a form, do a standard redirect afterwards. That way no POST info will be sent with the redirect. If you need to store things like an error message, use sessions.

Answer 2

Either;

• transfer to a different page

• insert using AJAX and inform the user with AJAX

• Create some kind of check to determine if the form is already posted (does the submit button contain a value for example)