[r2004-07-05 15:27:11 by vbenzake] Empty log message

Original author: vbenzake
Date: 2004-07-05 15:27:11+00:00

web/tutorial/queries.xml

@@ -295,13 +295,83 @@ optimiser automatically translates the latter into a pure pattern one
 </p>
 </section>
 <section title="Joins">
+
+
 <p>
-TO BE DONE
+This example is the exact transcription of query Q5 of XQuery use cases.
+We first give the corresponding CDuce types. We leave the user in charge of  creating the corresponding relevant values.
 </p>
+
+<sample><![CDATA[
+type Bib = <bib>[Book*] 
+type Book = <book year=String>[Title (Author+ | Editor+ ) Publisher Price]
+type Author = <author>[Last First]
+type Editor = <editor>[Last First Affiliation]
+type Title  = <title>[PCDATA]
+type Last  = <last>[PCDATA]
+type First  = <first>[PCDATA]
+type Affiliation = <affiliation>[PCDATA]
+type Publisher  = <publisher>[PCDATA]
+type Price  = <price>[PCDATA]
+]]>
+</sample>
+<p>
+The queries are expressed first in an XQuery-like style, then in a pure pattern style: the first pattern-based query is the one produced by the automatic translation from the first one. The last query correponds to a pattern aware programmer's version.
+</p>
+
+<p>
+XQuery style
+</p>
+<sample><![CDATA[
+<books-with-prices>
+select <book-with-price>[t1 
+              <price-amazon>([p2]/_) <price-bn>([p1]/_)]
+from b in [biblio]/Book ,
+     t1 in [b]/Title,
+     e in [amazon]/Entry,
+     t2 in [e]/Title,
+     p2 in [e]/Price,
+     p1 in [b]/Price
+ where t1=t2 
+]]>
+</sample>
+
+<p> Automatic translation of the previous query into a pure pattern (thus more efficient) one </p>
+<sample><![CDATA[
+<books-with-prices>
+select <book-with-price>[t1 <price-amazon>x11 <price-bn>x10 ]
+from <_>[(x3::Book|_)*] in [biblio],
+     <_>[(x9::Price|x5::Title|_)*] in x3,
+     t1 in x5,
+     <_>[(x6::Entry|_)*] in [amazon],
+     <_>[(x7::Title|x8::Price|_)*] in x6,
+     t2 in x7,
+     <_>[(x10::_)*] in x9,
+     <_>[(x11::_)*] in x8
+ where t1=t2
+]]>
+</sample>
+
+<p>  
+Pattern aware programmer's version of the same query (hence hand optimised).
+This version of the query is very efficient. Be aware of patterns.
+</p>
+
+<sample><![CDATA[
+<books-with-prices>
+select <book-with-price>[t2 <price-amazon>p2 <price-bn>p1]
+from <bib>[b::Book*] in [biblio],
+     <book>[t1&Title _* <price>p1] in b,
+     <reviews>[e::Entry*] in [amazon],
+     <entry>[t2&Title <price>p2 ;_] in e
+where t1=t2
+]]>
+</sample>
 </section>
 
 
 <section title="An unorthodox query: Formatted table generation">
+
 <p>
 The following program generates a 10x10 multiplication table:
 </p>