Sql Vs Xml

I already designed the concept for an online flash directory. In a way part of the interface will be similar to the following kirupa tutorial which access the information from an XML file:

http://www.kirupa.com/web/xml/examples/sortedgradeslist.htm

However, I know that there are a lot of open source PHP codes that work with SQL tables, which allow the user to view or modify information (I would like to emphasize that I am not a CS guy, but a designer instead. I am very much interested in learning Server-Side apps). So I was thinking about a second option to develop the back end of the directory, which can also be related to the following tutorial:

http://www.kirupa.com/developer/actionscript/flashphpxml_integration.htm

So are there any benefits of using one or the other option? I mean, will it be easier to work on flash loading an XML file and using built in sort functions, or instead to load variables in to flash from SQL using PHP?