Re: No exceptions?
Date: Fri, 30 Jun 2006 01:18:41 GMT
Bob Badour wrote:
> paul c wrote:
>> Bob Badour wrote: >> >>> paul c wrote: >>> >>>> J M Davitt wrote: >> >> ... >> >>>>> It almost seems as though you want to declare an analogue for DUM, >>>>> syntax-check some expressions, and add attributes to your relation >>>>> with the confidence that your expressions are still correct. >>>> >>>> Not exactly how I thought of it, but I think that's fair, after all, >>>> one can add attributes, subject to one's external conception, to >>>> relation definitions that don't have empty headings, in fact not >>>> that the observation is of any use, that seems to be what happens >>>> when one defines a relation with one attribute. >>> >>> I suggest an empty candidate key in a relation with any number of >>> attributes is closer. >> >> I don't catch your drift. If we are on the same page, then trying to >> equate a relation that has either no rows or one row with a relation >> whose name is mis-spelled is indeterminate. If doing that is the same >> then I would have to give up on my original question.
> You suggested that adding an attribute to a degree zero relation is a
> degree one relation. However, whether one adds one attribute or an
> arbitrary number of attributes is less important than the fact that the
> candidate key will have an empty set of attributes.
Thanks, I will try to ponder that in some way different from how I've been looking at it. Strictly speaking, I wasn't aware that one could 'add' an attribute to a relation, nor that any 'key' would persevere.
> Identifying the error condition is easy. The problem of identification
> only arises after you replace the error with DEE or DUM.
It seems (as usual) that I haven't explained myself well enough. While at the UI, I think most people would consider a spelling error an error, I would like, at a very low internal level, to ignore typo's of that sort, evaluate it as written, and give a result that is logically consistent (assuming that is logically possible). I want to postpone what error decisions are shown at the UI level.
p Received on Fri Jun 30 2006 - 03:18:41 CEST