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Posted by David Portas on 04/22/06 00:07
Lyle Fairfield wrote:
> We should be extremely careful when we convert nulls to values. Such
> conversion could lead to error. Often it is persons without strong
> grounding in mathematics and logic who make these conversions,
> increasing the likelihood of such error.
You think so? Nulls as formulated in SQL totally defy any standard
mathematics or logic. Any system that permits the predicate (x=x) to
evaluate to anything other than true isn't likely to win many votes
from persons with a strong grounding in mathematics. It is precisely
because nulls are so counter-intuitive that they lead to so many
mistakes in SQL. However, I do agree with your basic point that if you
regularly need to convert nulls like this it may indicate weakness in
your design or requirements.
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David Portas, SQL Server MVP
Whenever possible please post enough code to reproduce your problem.
Including CREATE TABLE and INSERT statements usually helps.
State what version of SQL Server you are using and specify the content
of any error messages.
SQL Server Books Online:
http://msdn2.microsoft.com/library/ms130214(en-US,SQL.90).aspx
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