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Re: Demo: Modelling Cost of Travel Paths Between Towns

From: Alan <not.me_at_rcn.com>
Date: Sat, 4 Dec 2004 08:29:40 -0500
Message-ID: <31dseiF3b7gtkU1@individual.net>

"Neo" <neo55592_at_hotmail.com> wrote in message news:4b45d3ad.0412031620.3f811ca3_at_posting.google.com...
> > One of the basic properties of an RDBMS is that there can be
> > underlying schema changes with no effect on existing code..
>
> Below script demonstrates that XDb2's queries (similar to code) are
> resilient to changes in "schema" regardless of what things are
> represented. Please show RM's equivalent/similar query that
> demonstrates similar resiliency. Having stated that you are paid for
> your time and are a professional, try to avoid NULLs and duplicate
> data. If you are able to do that we can then represent additional new
> things and see if the original queries continue to work.

LOOK - I HAVE ALREADY DONE THIS FOR YOU, TOLD YOU SEVERAL TIMES THAT I HAVE DONE THIS FOR YOU, AND THAT I WILL NOT DO IT AGAIN. SO STOP ASKING. GO LOOK THROUGH THE THREADS YOURSELF AND FIND IT.
>
> // XDb2's initial query to find things named john with age property
> // "SELECT %.age & %.name=john;"
>
> // Martian with no name or age
> CREATE *martian.cls = thing; // Create a martian class
> CREATE *; // Create a thing
> CREATE it.cls = martian; // Classify it as a martian
>
> // Martian with multiple names
> CREATE *; // Create a thing
> CREATE it.cls = martian; // Classify it as a martian
> CREATE it.name = +john;
> CREATE it.name = +luke;
>
> // Thing with multiple classes and multiple ages
> CREATE *plutonian.cls = thing;
> CREATE *;
> CREATE it.cls = martian;
> CREATE it.cls = plutonian;
> CREATE it.name = +john;
> CREATE it.age = +10;
> CREATE it.age = +"-3.14";
>
> // Two Venutians with same name and age
> CREATE *venutian.cls = thing;
>
> CREATE *;
> CREATE it.cls = venutian;
> CREATE it.name = +john;
> CREATE it.age = +very old;
>
> CREATE *;
> CREATE it.cls = venutian;
> CREATE it.name = +john;
> CREATE it.age = +very old;
>
> // Execute original query
> // (still works regardless of things represented)
> SELECT %.age & %.name=john;
Received on Sat Dec 04 2004 - 07:29:40 CST

Original text of this message

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