The Final NULL in the Coffin

The Final NULL in the Coffin

(Fabian Pascal)

This paper summarizes the drawbacks of the many-valued logic approach to missing data, and SQL’s problematic and poorly implemented flavor of three-valued logic via NULLs, and proposes a possible solution within the two-valued logic/relational framework. It (a) separates unknown and therefore missing data from “inapplicable” and therefore nonmissing data), and provides proper design guidelines to avoid the latter (b) treats missing data correctly as metadata and (c) yields logically correct answers with respect to the real world, without the complications and problematics of many-valued logic and SQL’s NULLs.

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