Query Through Multiple Files

[Michael Kay]

> I tried using 
> distinct-values(doc("1.xml"), doc("3.xml"), doc("4.xml"),  
> doc("2.xml"))//title, but I got the error that there should 
> be only 2 arguments. 

You didn't read my example carefully enough

distinct-values(( doc("1.xml"),
  doc("2.xml"),
  doc("3.xml"),
  doc("4.xml"))//ad)

Firstly, you want to find the set of titles and then take the distinct
values in this set: so the "//title" part needs to inside the argument to
distinct-values(). The way you've written it, you're taking four documents,
then eliminating duplicates, then taking the title elements within those
that are left.

Secondly, if you supply a sequence to a function that expects a single
argument then you need to double the parentheses, for example
sum((1,2,3,4,5)) or distinct-values((1,2,2,4,4)). That's to make it clear
you are passing one argument which is a sequence of five integers, not five
arguments that are single integers. IN your case you've called
distinct-values() with four arguments, rather than with a single argument
that is a sequence.

Michael Kay
http://www.saxonica.com/