Re: Nearest Common Ancestor Report (XDb1's $1000 Challenge)

> >Show me a method to determine person's class with the provided
> >solution and I will show you how it will fail if the data is changed
> >(ie the name of thing is changed from 'thing' to 'thingy' or
> >'object'). This failure will not occur with XDb1.
>
> [For Sol1] SELECT things.thing, classes.class
> FROM things LEFT JOIN classes ON classes.thing = things.thing
> WHERE things.thing = 'john'
>
> [For Sol2] SELECT things.thingName, classes.className
> FROM things LEFT JOIN ClassOfThings ON ClassOfThings.thing = things.thing
> INNER JOIN classes ON classes.class = ClassOfThings.class
> WHERE things.thingName = 'john'

The above are general methods for determining a thing's class(es) (which is what I meant, not just for john). If I substitute 'person' for 'john' both return 0 records. The methods do not work because the isa relationship between person and thing in not encoded in the db as it was for john and person, mary and person, fido and dog, etc. Without being able to systematically determine that person isa thing, the db client cannot derive that john isa thing also. Received on Fri May 28 2004 - 06:38:41 CEST