SQL Server Developer Center: Introduction to XQuery in SQL Server 2005
Summary: This white paper provides an introduction to various features of XQuery implemented in SQL Server 2005 such as the FLWOR statement, operators in XQuery, if-then-else construct, XML constructors, built-in XQuery functions, type casting operators, and examples of how to use each of these features. Non-supported features of XQuery in SQL Server 2005 and workarounds are described in this article. It also presents three scenarios where XQuery is useful. (30 printed pages)
While I haven't had the chance to read through this I most definitely plan to. I have several comments...
...to make regarding SQL Server 2005 and SQL Server Express, the free SQL Server client that allows a feature subset and a few restrictions/limitations (e.g. You are unable to use SSE as an actual server-side implementation(or, in other words you can't have clients connect to you, acting as a master synchronization point. You must connect to a SQL Server 2005 server-side installation and use this to synchronize against), theres a 4GB size limitation, and a few others... you can view a summary of the restrictions here.)
But what you can do is pretty astounding, one of which is use XQuery to query XML documents stored within SQL Server Express.
Over the last two weeks I have been doing an extensive amount of work with SS2005 and SSE and to be quite honest I think we are about to see a fairly major paradigm shift in the way we think about application development and deployment as it pertains to data-instensive applications, especially those in which make heavy use of XML.
Why use SQL Server to store your XML documents when you can store them on the file system. While I will admit that when XML really first started to hit the dev scene in a big way (2000/1 time frame) (and even coming from an ASP/SQL Server dev background) I did wonder how the database companies such as Oracle and Microsoft et. Al. would respond. Not from a corporate Fortune 1000 (or probably better said, 5000) standpoint but for the common every day developer who didn't work for a company in whom relied on high-end SQL database engines to process their 100's of 1000's to many millions of transactions each and every day. In cases like this I saw a HUGE potential for loss of revenue due to this group of developers simply taking advantage of a finely tuned file system to access a well designed XML infoset.
As the last five years have progressed and especially over the last 12 months I definitely think the press took full advantage of the opportunity to really push this question, especially as we began to see really good open source native-XML database implementations such as eXist-db and Berkeley XML DB. IBM (wrongfully in my opinion) tried to take advantage of what most definitely was a lack of understanding as to just how XML-enabled SQL Server was, even in its current '2000' release. Furthermore it could easily be seen by anybody who looked that Yukon (SQL Server 2005) had made HUGE native-XML inroads and in fact in many ways was more XML-enabled than anything IBM had to offer. Definition and usage of terminology can be so easily abused by the press it seems almost a waste of time listening to what most of the news agency have to say anymore.
But thats well beyond the point of this post, better suited for a day when I've simply had enough of the crap that I'm reading and decide to tell anybody willing to listen all of my feelings on such matters and then some.
Pray that day never comes ;) :D
Fortunately for companies like Microsoft, Oracle, and a few others who have such fantastic talent as Dr. Micheal Rys (MS) and Dr. Daniela Florescu(Oracle - XQuery Editor) and the money to patiently do things the right way have been doing just that. While several other companies new to the database business saw potential to cash in on the next big thing in XQuery and as such rushed the stage with half baked products and questionable marketing campaigns companies like Microsoft, Oracle, Sleepy Cat Software, and in many way the open source eXist XML database engine have been methodically building quality products to truly answer to needs of their customers in regards to highly efficient and incredibly capable XML-enabled database engines.
While I haven't been able to spend any time with Oracles products I've heard nothing but fantastic things from various Oracle developers in whom I know for a fact know where they're talking about.
On the other hand, I have been able to spend some time with Microsoft's offerings and, as I have already mentioned, can honestly state that I believe we are about to see a MAJOR paradigm shift over the next few years in how we develop, deliver, update, and maintain our software applications as well as how we access the data securely stored within the confines of this POWERHOUSE relational data transactional platform. Whether we want to believe it or not or further except it or not, companies like MS, Oracle, and the others previously mentioned know what they're doing. And in cases such as Microsoft where I have a bit more experience and understanding and in some cases a little (read:tiny amounts) extra information not available to everyone -- and especially with the recent addition (6 months) of Mike Champion to the XML WebData team -- it is my belief that the table has been set (no pun intended) and readied. Where we are now and where we will be in less than 2 years... well... quite simply, things will look absolutely NOTHING like they do today and VERY MUCH like what MANY people for several years have been foretelling, suggesting patience but knowing they wouldn't get it.
Why are we not there yet? Well, that in and of itself would require vast amounts of insider knowledge of which I most definitely do not have. But like a lot of you, I have my ideas and in some cases I feel pretty confident in my ideas being pretty close to spot on.
But thats of no real great worth. The bottom line, no matter how or why, is that the infrastructure has simply not been in place to take us from the current "idleing" perception to the 500/MPH rocket-powered flight down the Great Salt Lake Salt Flats proving once and for all that the future looks bright; and its not very far away.
Can I just suggest one thing? If you're not already, pay attention to whats going on in SQL Server land at Microsoft. Big things are about to happen. Really, REALLY, REALLY Big things.
This article (the original reason behind this post) seems to be a fantastic start to getting yourself primed and tuned to begin using XQuery in your daily development. I know I have been already (I told you I really do like XQuery; for what it was intentionally designed for :) and can only see this usage increasing based on what I have seen so far.
Be smart, get ready.