$sql = "INSERT INTO Data (Name, Description,Photo,Buy,Sell) VALUES ('"$_POST['name']"','"$_POST['description']"','"$_POST['photo']"','"$_POST['buy']"','"$_POST['sell']"'"));

$sql = "INSERT INTO Data (Name, Description,Photo,Buy,Sell) VALUES (?,?,?,?,?)";
$stmt = $pdo->prepare($sql);
$stmt->execute([$_POST['name'], $_POST['description'], $_POST['photo'], $_POST['buy'],$_POST['sell']]);

$sql = "INSERT INTO Data (Name, Description,Photo,Buy,Sell) VALUES ('$_POST[name]','$_POST[description]','$_POST[photo]','$_POST[buy]','$_POST[sell])";