<?php
// EDIT: Your mysql database account information
$username = "arduino01";
$password = "123456789";
$database = "rfid";
$tablename = "test";
$localhost = "localhost";
// Check Connection to Database
$db_connect = mysqli_connect($localhost, $username, $password);
$db_select = mysqli_select_db($db_connect, $database);

$request= $_GET['request'];
$validation = mysqli_query($db_connect, "SELECT * FROM $tablename WHERE yourdata ='$request'");
 if(mysqli_num_rows($validation) === 0){
    $sql = "INSERT INTO $tablename(Data) VALUES ($request)";
    mysqli_query($db_connect, $sql);
 }
?>