insert-post.php

<?php

if(!isset($_POST['username'], $_POST['title'], $_POST['content'])) {
	header('Location: new-post.html');
	exit();
}

$servername = "localhost";
$username = "hackeruser";
$password = "Aa123456";
$dbname = "reuven1";

//create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
	die("connection failed: " . $conn->connect_error);
}

$sql = "INSERT INTO posts (username, title, content) VALUES ('".$_POST['username']."', '".$_POST['title']."', '".$_POST['content']."')";

if ($conn->query($sql) === TRUE) {
	echo "New record created successfully";
} else {
	echo "Error: ".$sql."<br>".$conn->error;
}

$conn->close();

// Eventually redirect to index
header('Location: index.php');

?>