Re: Constraints and Functional Dependencies
Date: Wed, 28 Feb 2007 01:07:35 +0100
paul c wrote:
> mAsterdam wrote:
>> Mp (Marshall/paul) referential integrity =def=
>> (using レ = katakana re for references)
>> R(a) レ S(b) ≡
>> ∀R(a): ∃S(b)| a=b
>> Classic referential integrity (no need, says paul c)
>> (ル = ru for references unique)
>> R(a) ル S(b) ≡
>> ∀R(a): ∃!S(b)| a=b
> ... Congrats.
(ii) doesn't need that b should be /defined/ as ck for relvar S (which would really be the classic ri), just that it /could/ be ck in the current relvalue S.
About the notation:
Note (not afterthought):
1. that the katakana re, レ for _reference_ could read as 'check' (it looks like a check mark),
verbose 'check that there is',
2. the katakana ru, ル for _reference_unique_ as 'check one' (it looks like a check mark with a sloppy 1 before it), verbose 'check that there is only one'.
How about that for sugar coating ;-) Received on Wed Feb 28 2007 - 01:07:35 CET