PHP doesnt display anything - php

Question

Hi guys I'm new to PHP and I'm trying to display all info in my admin table. When I test my PHP file it gives me a blank page, here is my php code. There's no error but I get a blank page and nothing was returned when I execute it.
<?php
require('connect.inc.php');
require('admin.config.inc.php');
require('core.inc.php');
if (!empty($_POST)) {
//initial query
$query = "SELECT * FROM admin where username = :user";
$query_params = array(':user' => $_POST['username']);
//execute query
try {
$stmt = $db -> prepare($query);
$result = $stmt -> execute($query_params);
} catch (PDOException $ex) {
$response["success"] = 0;
$response["message"] = "Database Error!";
die(json_encode($response));
}
// Finally, we can retrieve all of the found rows into an array using fetchAll
$rows = $stmt -> fetchAll();
if ($rows) {
$response["success"] = 1;
$response["message"] = "Post Available!";
$response["users"] = array();
foreach($rows as $row) {
$user = array();
$user["username"] = $row["username"];
$user["designation"] = $row["designation"];
$user["middlename"] = $row["middle_initial"];
$user["firstname"] = $row["first_name"];
$user["lastname"] = $row["last_name"];
//update our repsonse JSON data
array_push($response["users"], $user);
}
// echoing JSON response
echo json_encode($response);
} else {
$response["success"] = 0;
$response["message"] = "No user available!";
die(json_encode($response));
}
} else {}
?>

Answer 1

Put this at the head of the script to see what response you get. Then others may be able to help you according to the error you get.
ini_set('display_errors',1);
error_reporting(E_ALL);
I see you have also began with:
if (!empty($_POST)) {
}
$_POST IS An associative array of variables passed to the current script via the HTTP POST method.
$_POST is defined where. this should be some thing like $_POST['user']

Answer 2

You begin with:
if (!empty($_POST)) {
which is empty by default, so you go directly to the else statement which is empty as well!

Answer 3

You are declaring $user = array(); inside the loop, It has to be outside of the loop
$user = array();
foreach($rows as $row) {
$user["username"] = $row["username"];
$user["designation"] = $row["designation"];
$user["middlename"] = $row["middle_initial"];
$user["firstname"] = $row["first_name"];
$user["lastname"] = $row["last_name"];