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Nulls, three-valued logic, and ambiguity in SQL

critiquing date's critique
Authors: Claude Rubinson;

Nulls, three-valued logic, and ambiguity in SQL

Abstract

Date's popular critique of SQL's three-valued logic [4, 3] purports to demonstrate that SQL queries can produce erroneous results when nulls are present in the database. I argue that this critique is flawed in that Date misinterprets the meaning of his example query. In fact, SQL returns the correct answer to the query posed; Date, however, believes that he is asking a different question. Although his critique is flawed, I agree with Date's general conclusion: SQL's use of nulls and three-valued logic introduces a startling amount of complexity into seemingly straightforward queries.

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selected citations
These citations are derived from selected sources.
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
7
Average
Top 10%
Average
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