Generate XML file with document constructor from xquery

Question

I have problem to generate .xml file from xquery. Here is my code:

document {
<?xml version="1.0" encoding=UTF-8" href="C:\Users\User\Desktop\UDBXML-lab\artist.xml"?>,
<ARTISTS>
{
for $a in doc("Artists.xml")//ARTIST
return <ARTIST ID="{$a/@ID}">
{$a/*}
{
for $b in doc("Groups.xml")//GROUP
where $a/@ID = $b/@ID
return $b
}
{
for $b in doc("DJ.xml")//DJ
where $a/@ID = $b/@ID
return $b
}
{
for $b in doc("Singers.xml")//SINGER
where $a/@ID = $b/@ID
return $b
}
</ARTIST>
}
</ARTISTS>
}

I get error:

A processing instruction must not be named 'xml' in any combination of upper or lower case.

But I don't know which processing instruction to set to save this query in document.

Which tool or XQuery processor do you use? The XQuery document constructor does not take any XML declaration nor any file name. Saving/serializing to a file is part of the XQuery processor API or GUI or use of the `put` function or a file module. — Martin Honnen, May 31 '20 at 16:55

score 1 · Answer 1 · answered May 31 '20 at 01:47

You need to leverage XQuery prolog declarations. Here is how to do it.

base-uri declaration specifies a directory for all XML files. The other two declarations will create an XML prolog with desired settings.

XQuery

xquery version "3.0";
declare base-uri 'C:\Users\User\Desktop\UDBXML-lab\';
declare option output:omit-xml-declaration "no";
declare option output:encoding "UTF-8";

<ARTISTS>
{
for $a in doc("Artists.xml")//ARTIST
return <ARTIST ID="{$a/@ID}">
{$a/*}
{
for $b in doc("Groups.xml")//GROUP
where $a/@ID = $b/@ID
return $b
}
{
for $b in doc("DJ.xml")//DJ
where $a/@ID = $b/@ID
return $b
}
{
for $b in doc("Singers.xml")//SINGER
where $a/@ID = $b/@ID
return $b
}
</ARTIST>
}
</ARTISTS>

Generate XML file with document constructor from xquery

1 Answers1