You started your session, then you asked if it is a post request or not.
Then you checked if that post variable isset() to start your code.
Unfortunately the code never run and you have no idea what happened.
Add the 2 lines in red in the following code to find out which post variables exist.

 

<?php
session_start();
if ($_SERVER[‘REQUEST_METHOD’] == ‘POST’)
{

// the 2 lines for your debug
foreach ($_POST as $key => $value)
echo “Field “.$key.” is “. htmlspecialchars($value).”<br>”;

if (isset($_POST[“customer_id”]))
{

// Your code

}

}

?>