SimpleXML and insert data into MySQL using PDO - php

Question

I have used SimpleXML to get XML data from a source that required authenticiation. Using cURL I have been able to get back a result. However when I have tried to get the data into a MySQL database nothing is inserted.
Now I think it's because I have not done something to the XML data. However I am a newbie to XML data and have always worked with database stuff so could do with some help.
I have had a look around and I'm probably duplicating another question on here, but my confusion is over what I am looking at. If I can figure out the "why", I'll get to the "how"!.
Here is the output I get:
SimpleXMLElement Object
(
[bookingDataResponse] => SimpleXMLElement Object
(
[bookingDataResult] => <Bookings><SupplierCode>ABCD</SupplierCode><ServiceName>Service 1</ServiceName><UnitCode>ABC123</UnitCode></Bookings><Bookings><SupplierCode>XYZ</SupplierCode><ServiceName>Service 2</ServiceName><UnitCode>XYZ123</UnitCode></Bookings>
)
)
I presume that I need to transform the result of the above and then get that data to insert into the database. However this is where I am stuck.
I'll use PDO and a foreach to get the data into the database, but any help on getting to that point would be very useful guys.
Cheers
UPDATE # 11:18GMT:
This update covers the database insert I have coded:
$servername = "xxx.xxx.xxx.xxx";
$username = "username";
$password = "password";
$dbname = "myDatabase";
$db_cstr = "mysql:host=" . $servername . "; dbname=" . $dbname;
$conn=new PDO($db_cstr, $username,$password);
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$conn->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);
foreach ($parser->bookingDataResponse->bookingDataResult->Bookings as $row)
{
$SupplierCode = ($row->SupplierCode);
$UnitCode = ($row->UnitCode);
$stmt = $conn->prepare("INSERT INTO `bookingData` (`SupplierCode`, 'UnitCode') VALUES (?,?)");
$stmt->execute(array($SupplierCode,$UnitCode));
}