how to specify a BaseX database from a FLOWR xquery?

Question

How can I get all the titles with a FLOWR query against a specified database?

Specifying a document works:

thufir@dur:~/basex/microsoft$ 
thufir@dur:~/basex/microsoft$ basex titles.xq 
[warning] /usr/bin/basex: Unable to locate /usr/share/java/jing.jar in /usr/share/java
<title>Creepy Crawlies</title>
<title>Lover Birds</title>
<title>MSXML3: A Comprehensive Guide</title>
<title>Maeve Ascendant</title>
<title>Microsoft .NET: The Programming Bible</title>
<title>Midnight Rain</title>
<title>Oberon's Legacy</title>
<title>Paradox Lost</title>
<title>Splish Splash</title>
<title>The Sundered Grail</title>
<title>Visual Studio 7: A Comprehensive Guide</title>
<title>XML Developer's Guide</title>thufir@dur:~/basex/microsoft$ 
thufir@dur:~/basex/microsoft$ 
thufir@dur:~/basex/microsoft$ cat titles.xq 
for $x in doc("books.xml")/catalog/book
order by $x/title
return $x/title 
thufir@dur:~/basex/microsoft$ 

but that's against a stand-alone xml document and not from within the BaseX console itself. How can I use the name for the database directly in the FLOWR for BaseX to reference?

> 
> xquery //book[@id="bk112"]/title
<title>Visual Studio 7: A Comprehensive Guide</title>
Query executed in 1.47 ms.
> 
> xquery /
<catalog>
  <book id="bk101">
    <author>Gambardella, Matthew</author>
    <title>XML Developer's Guide</title>
    <genre>Computer</genre>
    <price>44.95</price>
    <publish_date>2000-10-01</publish_date>
    <description>An in-depth look at creating applications 
      with XML.</description>
  </book>
  <book id="bk102">
    <author>Ralls, Kim</author>
    <title>Midnight Rain</title>
    <genre>Fantasy</genre>
    <price>5.95</price>
    <publish_date>2000-12-16</publish_date>
    <description>A former architect battles corporate zombies, 
      an evil sorceress, and her own childhood to become queen 
      of the world.</description>
  </book>
  <book id="bk103">
    <author>Corets, Eva</author>
    <title>Maeve Ascendant</title>
    <genre>Fantasy</genre>
    <price>5.95</price>
    <publish_date>2000-11-17</publish_date>
    <description>After the collapse of a nanotechnology 
      society in England, the young survivors lay the 
      foundation for a new society.</description>
  </book>
  <book id="bk104">
    <author>Corets, Eva</author>
    <title>Oberon's Legacy</title>
    <genre>Fantasy</genre>
    <price>5.95</price>
    <publish_date>2001-03-10</publish_date>
    <description>In post-apocalypse England, the mysterious 
      agent known only as Oberon helps to create a new life 
      for the inhabitants of London. Sequel to Maeve 
      Ascendant.</description>
  </book>
  <book id="bk105">
    <author>Corets, Eva</author>
    <title>The Sundered Grail</title>
    <genre>Fantasy</genre>
    <price>5.95</price>
    <publish_date>2001-09-10</publish_date>
    <description>The two daughters of Maeve, half-sisters, 
      battle one another for control of England. Sequel to 
      Oberon's Legacy.</description>
  </book>
  <book id="bk106">
    <author>Randall, Cynthia</author>
    <title>Lover Birds</title>
    <genre>Romance</genre>
    <price>4.95</price>
    <publish_date>2000-09-02</publish_date>
    <description>When Carla meets Paul at an ornithology 
      conference, tempers fly as feathers get ruffled.</description>
  </book>
  <book id="bk107">
    <author>Thurman, Paula</author>
    <title>Splish Splash</title>
    <genre>Romance</genre>
    <price>4.95</price>
    <publish_date>2000-11-02</publish_date>
    <description>A deep sea diver finds true love twenty 
      thousand leagues beneath the sea.</description>
  </book>
  <book id="bk108">
    <author>Knorr, Stefan</author>
    <title>Creepy Crawlies</title>
    <genre>Horror</genre>
    <price>4.95</price>
    <publish_date>2000-12-06</publish_date>
    <description>An anthology of horror stories about roaches,
      centipedes, scorpions  and other insects.</description>
  </book>
  <book id="bk109">
    <author>Kress, Peter</author>
    <title>Paradox Lost</title>
    <genre>Science Fiction</genre>
    <price>6.95</price>
    <publish_date>2000-11-02</publish_date>
    <description>After an inadvertant trip through a Heisenberg
      Uncertainty Device, James Salway discovers the problems 
      of being quantum.</description>
  </book>
  <book id="bk110">
    <author>O'Brien, Tim</author>
    <title>Microsoft .NET: The Programming Bible</title>
    <genre>Computer</genre>
    <price>36.95</price>
    <publish_date>2000-12-09</publish_date>
    <description>Microsoft's .NET initiative is explored in 
      detail in this deep programmer's reference.</description>
  </book>
  <book id="bk111">
    <author>O'Brien, Tim</author>
    <title>MSXML3: A Comprehensive Guide</title>
    <genre>Computer</genre>
    <price>36.95</price>
    <publish_date>2000-12-01</publish_date>
    <description>The Microsoft MSXML3 parser is covered in 
      detail, with attention to XML DOM interfaces, XSLT processing, 
      SAX and more.</description>
  </book>
  <book id="bk112">
    <author>Galos, Mike</author>
    <title>Visual Studio 7: A Comprehensive Guide</title>
    <genre>Computer</genre>
    <price>49.95</price>
    <publish_date>2001-04-16</publish_date>
    <description>Microsoft Visual Studio 7 is explored in depth,
      looking at how Visual Basic, Visual C++, C#, and ASP+ are 
      integrated into a comprehensive development 
      environment.</description>
  </book>
</catalog>
Query executed in 1.59 ms.
> 

or with the GUI:

using Microsoft data, or from w3schools also.

Answer 1

For the basex command line script you seem to use there is the -i option you can use to set a named database as the context or to use an input file for that so basex -i mydb xquery.xq runs your xquery.xq with the database called mydb as the context of the query.

Answer 2

From Martin's answer, this is the concrete xquery and command:

thufir@dur:~/basex/microsoft$ 
thufir@dur:~/basex/microsoft$ basex -i w3school_data titles.xq
<title>Creepy Crawlies</title>
<title>Lover Birds</title>
<title>MSXML3: A Comprehensive Guide</title>
<title>Maeve Ascendant</title>
<title>Microsoft .NET: The Programming Bible</title>
<title>Midnight Rain</title>
<title>Oberon's Legacy</title>
<title>Paradox Lost</title>
<title>Splish Splash</title>
<title>The Sundered Grail</title>
<title>Visual Studio 7: A Comprehensive Guide</title>
<title>XML Developer's Guide</title>thufir@dur:~/basex/microsoft$ 
thufir@dur:~/basex/microsoft$ 
thufir@dur:~/basex/microsoft$ cat titles.xq 
for $x in /catalog/book
order by $x/title
return $x/title 
thufir@dur:~/basex/microsoft$ 

I took a stab at the xquery and it worked! thanks Martin.