<?php
$hostname = 'localhost';
$username = 'root';
$password = '';
$db_name = 'somedb';
$conn = mysqli_connect($hostname, $username, $password, $db_name);
if (isset($_POST['abc'])){
    $date_today = date('Y-m-d');
    $somecount=("INSERT INTO sometable (today,somecount) VALUES ('".$date_today."', '') ON DUPLICATE KEY UPDATE somecount=somecount+1");
    mysqli_query($conn, $somecount);
}

?>

<form method="post" action="some.php">
    <input type="submit" name="abc">
</form>