Dan McCreary wrote about his Teaching XSLT vs. Teaching XQuery experience.
At DataDirect we have also good experience teaching XQuery, and a developer with some SQL experience is definitely not in disadvantage. A lot of the query concepts in SQL are easily mapped into XQuery. Priscilla Walmsley’s book, which I highly recommend, devotes a complete chapter on this topic.
As a SQL developer you might be wondering, why using XQuery to talk to my favorite relational database? Minollo blogged about it a while back. Yes there are some good reasons to have XQuery in your toolbox in addition to good old SQL.
XQuery is the natural choice to bridge the relational and XML world, with products like XML Converters you can easily extend this from XML to the complete EDI world. And tools like the XQueryWebService Framework make it trivial to build powerful data services that query, aggregate and update multiple data sources.
Increased developer’s productivity is great, but equally important is performance and scalability. This is exactly one of the focus areas of DataDirect XQuery, for example by taking full advantage of your current SQL investments.