Posted by Erland Sommarskog on 10/01/28 11:41

figital (mharen@gmail.com) writes:
> I agree with Doug. We usually use reals to hold our percentages. In the
> db, a 5.5% discount would look like .055.........
>
> Because, in effect, that's really what 5.5% represents.

In our shop we can never make up our mind... So some of the percentages
are stored as aba_percent, others as aba_fraction and yet others as float.
aba_percent is just an alias for "float" but the name implies that it is
a percentage, and that you should divide with 100 before use. aba_fraction
is float, and constrained to be between 0 and 1. Multiply with 100 before
display, and divide by 100 before storing. Those that just float, can
hold values outside the range [0..1]. (I have considered a constraint
to keep them between -10 and 10, but that is a risky business, as one
day 1200% may be a correct value.)

The problem with storing percentages as fraction, is that some developers
make the entry forms a carbon of the data model, so they don't display
the fraction as a percentage, but as a fraction...


--
Erland Sommarskog, SQL Server MVP, esquel@sommarskog.se

Books Online for SQL Server 2005 at
http://www.microsoft.com/technet/prodtechnol/sql/2005/downloads/books.mspx
Books Online for SQL Server 2000 at
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