Last week I wrote about XMLTABLE as the "all-in-one" function because it is a very versatile function. Many DB2 customers are using XMLTABLE to allow existing relational applications co-exist with XML data either in the database or on the wire. The first is obvious, XML data is stored in the database and made available by a relational table (view) built on top of the XML data. If XML data is fed to (not into) the database, e.g., via queues, it doesn't necessarily mean it needs to be stored in the XML format. Some customers use the XML format to exchange data with other companies or agencies (think of product information, tax data, payment information, brokerage data, etc.), but process only data stored in purely relational format - no XML involved. What they do is to feed their incoming XML data into the XMLTABLE function and then store the table output in the database.
Today's title "Explained, the easy way" refers to reusing existing excellent information. Two of my colleagues wrote a 2-part article about XMLTABLE that I recommend reading. Part 1 which is titled "Retrieving XML data in relational format" gives an overview, part 2 has lots of examples and is labeled "Common scenarios for using XMLTABLE with DB2".