The UNKNOWN Factor

Authors

Abstract

Sometimes conditions might produce UNKNOWN instead of an expected Boolean value of TRUE or FALSE. If you have several Boolean values ANDed, ORed, and NOTed together, and if one value is UNKNOWN, it might not be obvious what the final combined value is. This article presents an example of an UNKNOWN value that propagates its insidious effects, producing a surprising result set.

Keywords

Null values, boolean logic, Oracle8i

Subject

Technical Advice - Oracle8i

Journal

Oracle Professional Newsletter, Vol. 8, #3, pp. 12-19, Farion Grove (Editor), March 2001

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