Sunday, June 11, 2017

What Meaning Means: Business Rules, Predicates, Integrity Constraints and Database Consistency

Note: After the initial posting I corrected some errors. Readers of the initial post early Sunday should re-read.

Whether we like it or not,
"All semantics that can be formalized in FOPL--including verbs such as ‘supplies’—formalize as constraints. We use constraints to reduce the number of permissible interpretations—meanings—of the purely abstract FOPL deductive system. Codd did bring integrity to the forefront by making it an explicit component of a formal data model, but that does not mean that all the semantics that can be captured formally, have been captured in the standard description of RDM, let alone supported in products. In 1979 Codd described a way to "capture" semantics using the relational formalism beyond the then current understanding. That formalism doesn't tell you how to discover semantics, but if you have them, he shows (at least to some degree) how to express those semantics relationally." --David McGoveran
Read it all. 

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