stop inserting data in the database when refreshing the page

Question

I am looking for a way to stop inserting or sending data in the database when refreshing the page.

here is my code:

user_details_page.php

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Answer 1

confirm_page.php:

if (isset($_POST['submit'])) 
{
$user= $_POST['username'];
$email = $_POST['useremail'];
$pass= $_POST['password']; 

mysql_query("INSERT INTO table (username, useremail, email) VALUES ('$username','$useremail','$email')"); // <-- missing endquote and bracket here

header('Location: somewhere_else.php');
exit;
}