Constructing XML data

Results of a query can be wrapped in XML:

  WHERE <bib><book>
          <publisher> <name>"Addison-Wesley" </> </>
          <title>  $t </>
          <author> $a </>
        </></> IN "bib.xml"
  CONSTRUCT <result>
               <author> $a </>
               <title>  $t </>
            </>

results are grouped in elements.
the pattern matches once for each author, which may give duplicates of books.

The following example data:

<bib> <book year="1995">  <title>An Introduction to Database Systems </title> <author><lastname>Date </lastname></author> <publisher><name>Addison-Wesley </name> </publisher> </book> <book year="1998"> <title>Foundation for Object/Relational Databases</title> <author><lastname>Date </lastname></author> <author><lastname>Darwen </lastname></author> <publisher><name>Addison-Wesley </name> </publisher> </book> </bib>

<bib> <book year="1995"> <!-- A good introductory text --> <title>An Introduction to Database Systems </title> <author><lastname>Date </lastname></author> <publisher><name>Addison-Wesley </name> </publisher> </book> <book year="1998"> <title>Foundation for Object/Relational Databases</title> <author><lastname>Date </lastname></author> <author><lastname>Darwen </lastname></author> <publisher><name>Addison-Wesley </name> </publisher> </book> </bib>

produces the output:

<XML> <result> <author><lastname>Date </lastname></author> <title>An Introduction to Database Systems </title> </result> <result> <author><lastname>Date </lastname></author> <title>Foundation for Object/Relational Databases</title> </result> <result> <author><lastname>Darwen </lastname></author> <title>Foundation for Object/Relational Databases</title> </result> </XML>