Preparing simple query for PDO connection - mysql

Question

I would like to prepare PDO statement and convert results to JSON in PHP. I managed to connect to database by following method:
class DB_CONNECT {
function __construct() {
$this->connect();
}
function __destruct() {
$this->close();
}
function connect() {
$root = getenv("DOCUMENT_ROOT");
require_once ($root.'/db/db_config.php');
try
{
$db = new PDO('mysql:host='.DB_SERVER.';dbname='.DB_DATABASE.';charset=utf8;port='.DB_PORT, DB_USER, DB_PASSWORD);
$db->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
echo 'OK';
return $db;
}
catch (PDOException $e)
{
print "Connection error!: " . $e->getMessage() . "<br/>";
die();
}
}
function close() {
$db = null;
}
PHP, where I make statements looks like this:
$root = getenv("DOCUMENT_ROOT");
require_once ($root.'/db/db_connect.php');
$db = new DB_CONNECT();
$statement=$db->prepare("SELECT name, surname FROM lecturer");
$statement->execute();
$results=$statement->fetchAll(PDO::FETCH_ASSOC);
echo json_encode($results);
When I run this PHP, I'm getting only OK message, that the connection went successfully. What's wrong with that query code?

Answer 1

What does your error log say? From your code, I can tell you that $db doesn't contain a PDO object, as you don't return anything in the constructor of DB_CONNECT. So $db is an object of type DB_CONNECT, not of type PDO, and thus doesn't have prepare as a method.
For a quick fix, change
$db = new DB_CONNECT();
to
$db = DB_CONNECT::connect();
and make connect static.