SQL instead of XQuery

[Dmitry Turin <dev3os@narod.ru>]

a,

arbvc> Dmitry Turin napsal(a):
>>>>   Rational model is graph, but xml model is tree -
>>>> so xml model is sub-set of rational model (i.e. you are wrong).
arbvc> First, XML is also graph (did you forget about IDREF?)

IDREF is copy of other (relational) technology,
this is not so, what XML itself is.

Central idea of XML is enclosed elements.

P.S. When you are using IDREF, you are simply making snapshort of
rational database - not readable, not convenient.
Prepearing snapshort, XML has no any advantage before other (textual)
formats.

arbvc> It is very simple to map the relational database into XML

Not very, but only simple (for non-programmers, with which i speak in
my place).

arbvc> mapping in the another direction is brings
arbvc> many difficulties, mainly when you do additional updates in the XML
arbvc> document it is not easy to follow these changes in RDBMS.

Do you read http://sql50.euro.ru/sql5.11.1.ppt slides 7-9, 24-27 ?
Can you point at least one difficulty ???

For comparison, i can point difficulties with SQL/XML function,
with Microsoft's 'select ... for xml'.

arbvc> Therefore, I would say teoretical the models are equal

Agreed (mathamatically equal).

arbvc> but practicaly relational database is subset of the XML database.

Opposite. Practically IDREF is not used by wide-spread users,
practically an element is enclosed into an element,
practically XML is used as tree (and it's reasonable,
because snapshort with IDREF is uncomfortable to read and
reconstruct in head).


Dmitry Turin
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