Interview with MVP Michael Coles.

Posted: April 8, 2010 in Uncategorized

 We are again graced with another author not only commenting on their chapter in the form of a blog post but we’ve also been able to ask Michael (Blog | SQL Server Central) a few questions.

Michale was picked for the chapter he did in the SQL Server Deep Dives Book.  And in my opinion the book you must have now. We are reviewing each chapter and on top of it we are trying to interview each Author.  You can find the chapter review here.


Q: What one topic or section of your chapter in the Deep Dives book would you say is the place where most people working with xQuery make the most mistakes?

A: I would say the biggest issue people face with XQuery is the learning curve.  It’s really not as steep as people think, but because XML isn’t relational you basically need to learn a new set of methods to query it.  Once you get into though, most people realize that XQuery uses a familiar “path syntax” that’s very similar to standard operating system directory structures (Windows or *nix style).

Q: How did you start your career with SQL Server and why did you move to learning more about xQuery?

A: I actually started by supporting applications that ran against SQL 6.0 on NT 3.51 way back in the day.  My interest in XQuery actually started back in 1998 when the XML 1.0 Recommendation came out.  I thought it was really interesting and potentially useful technology, but I ran up against the limitations pretty quickly.  The main problems were no data typing (everything’s a string) and no simple way to query content (lots of loops and custom parsing).  When XPath came out a year later it fixed some issues, but left some others.  XQuery and XML Schema really fix a lot of other issues.  SQL 2000 XML support in the database was really overly-complicated, so when SQL 2005 came out with the XML data type I got really excited by the possibilities.

Q: What makes xQuery such an important part of SQL Server and how do you see it being leveraged in the �Real World�?

A: A lot of people don’t believe XML is contradictory to the relational model.  I don’t argue on that topic–there are plenty of people who are willing to argue both sides, so there’s not a whole lot I could add to the argument.  One of the most interesting aspects (to me) is that you can utilize SQL server functionality to convert relational data to XML, shred XML to relational data, etc. without ever persisting XML in the database.  So even the most ardent relational purist can take advantage of XML without storing it in the database.

Q: Do you believe that a lot of companies using the XML features in SQL Server, do you see this as a trend that will grow?

A: Yes, there are a lot of companies using SQL Server’s XML features.  Some of the most common features I see in use are the FOR XML feature to format relational data as XML and XML “shredding” (turning XML into relational data).  I think as Microsoft improves SQL Server’s XML support and performance, people will really start seeing the advantages of additional features like XML Schema and XML Indexes.

 Q: What’s next for you? What projects are you looking at for the future?

A: For now I’m back to independent consulting, with a few articles and presentations in the short term.  I’m working on a book with Vijaya Kadiyala in the longer term.  After that, who knows…


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