XML or Sql or ??

Hi

I'm developing my first app for iOS using Flashbuilder 4.6 and need to have a database to keep track of certain items, probably no more than 20 items per record (including username and password) in a single table for a single user. 

I don't want to use server technology but want to keep the data on the device.   My question is should I use XML or SQL or some other way to store the data on the device.

Any guidance would be appreciated.

Thanks.