Re: Interesting article: In the Beginning: An RDBMS history
From: paul c <toledobythesea_at_oohay.ac>
Date: Thu, 06 Apr 2006 15:37:18 GMT
Message-ID: <OAaZf.2571$_u1.1765_at_pd7tw2no>
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> In my experience, it's rather common to use that phrase for foreign keys.
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> Hm?
Date: Thu, 06 Apr 2006 15:37:18 GMT
Message-ID: <OAaZf.2571$_u1.1765_at_pd7tw2no>
Jon Heggland wrote:
> paul c wrote:
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>>I'm darned if I know what a "relationship between tables" is unless >>it's another table.
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> In my experience, it's rather common to use that phrase for foreign keys.
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In a 'standard' that people rely on to make exact decisions, what good is it to use it that way? Wouldn't it be better to say exactly what it is, for example, one projection is a subset of the other?
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>>For that matter, I don't know what the sql standard >>would mean by "table" (assuming it uses that word). I've assumed that >>it doesn't stand for a relation partly because it allows duplicates and >>nulls. Without those differences, I imagine an sql table still couldn't >>stand for any relation we choose because at least when I was using it >>ten or more years ago a row-column intersection contained only a single >>value, ie. some relations can't be expressed as one table.
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> Hm?
For sure, any single-rva-attribute relation, maybe others too.
p Received on Thu Apr 06 2006 - 17:37:18 CEST