XML from Data Base Examples tutorial
Making a Forest of XML elements by XMLAGG() function XMLAGG() function

## XMLAGG() function. Overview

XMLAGG is aggregate function that produces a forest of XML elements from the given list of xml elements. It concatenates the values returned from one column of multiple rows, unlike `XMLCONCAT`, which concatenates the values returned from multiple columns in the same row.

## Example 1

This example produces a forest of all 'Name' of the employees having the title 'Sales Representative' and places it into one top-level element:

      select XMLELEMENT ('SalesRepresentatives',
        XMLAGG (XMLELEMENT ('Name', "FirstName", ' ', "LastName")) )
        from "Demo"."demo"."Employees"
        where "Title"='Sales Representative';