Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!njin!princeton!phoenix!englandr
From: englandr@phoenix.Princeton.EDU (Scott Louis Englander)
Newsgroups: comp.databases
Subject: Representing missing values in databases
Message-ID: <9571@phoenix.Princeton.EDU>
Date: 24 Jul 89 05:54:34 GMT
Organization: Princeton University, NJ
Lines: 13

Does commercial database software generally have a way to represent
missing numbers?  I'm using Fox on the Mac, and the best i can do is use
a value (-99) that is unlikely to appear naturally in the data.  This is
problematic for fields that are, say, one character logical fields, etc.
I really do need to distinguish between 0 and missing, or false and
missing.

Other Mac software (e.g. Igor {scientific plotting}, compilers) uses the
special value NaN (Not a Number) for this purpose; it seems like it
would be simple enough to incorporate it in a program like FoxBASE.
-- 

                                               - Scott