auto table mapping
dent at highway1.com.au
Wed Sep 2 22:00:44 BST 1998
The context is our storing a report-writer output into a standalone
document so the same engine can later reparse the document, and allow user
We have a tree of report-writer objects, almost all of which link to one or
more database views.
An obvious shortcut is to put a lot of specialist attributes into our DTD
so that our structures are easily rebuilt.
I'm playing with the idea of having our parser able to recreate such a tree
in a fairly generic manner (ie: handle other people's XML :-).
The essential issue is the flattening of the bottom level. Instead of a
general tree, with leaves containing PCDATA (or b64-encoded images) we want
to recognise the situation where a number of sibling leaves are actually
fields in a single record.
Thus, two levels of the tree map to an internal 'table' object.
Nested elements which contain other PCDATA leaves would be modelled as
related tables (as an OORDBMS OOFILE models relationships as well as
The key assumptions here are
1) we will auto-generate some internal ID to track the relationships (I
haven't time for the complexities of XML-Data, and join keys may not be in
the exported data)
2) some portion of the DTD will fall into a pattern of 'tables' with
possible nested tables
3) inside this pattern, we may require you to explicitly bracket multiple
occurrences of an element inside another element so we can recognise a
nested table (ie: <student> can't contain multiple <grade> elements
directly, but needs <student> <results> <grade>)
Is there interest in discussing this further or should I just carry on and
implement something merely good enough for our immediate load/save
Andy Dent BSc MACS AACM, Software Designer, A.D. Software, Western Australia
OOFILE - Database, Reports, Graphs, GUI for c++ on Mac, Unix & Windows
PP2MFC - PowerPlant->MFC portability
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