I'm a complety newby in the xml stuff, and i have a very base question about it... i've been reading everything (ok, not really) but all what i found was about the meaning and philosofy of xml, nothing about real cases.

i'need to solve this example that is getting me crazy to figure out where xml would fit inside my brain... and then in my proyects.

I have a mysql or sql database and php making the queries and rendering the hole templates to html. My question is... would the chain with xml be this one?:

mysql -> xml -> php -> html

i mean: i have the data in a sql table, then i ask the database returning that in xml (yeah, with all the wonderfull uses you can do with it), then the php asks the xml file to render it to html...
opps, that sounds a very busy work in the server, isn't it?. I think i'm missunderstanding the point of this.

Let's go then... for example, amazon and those huge sites with millions of data, are they using xml as a database or sql as a database (or whatever database)?, asp or php (or other server side scripts) to render that to html or just everything under xml with xls alone?

Ufff... if someone could answer me with a real case (ok, fiction case if you want, but not cryptic xml matters... please)
i would try to study it becouse it seems something very useful, or at least something everybody use!

Thanx in advance.