* Petras Virzintas <[EMAIL PROTECTED]> wrote on 15.01.01 23:55:
> The column type "FLOAT" seems to be flaky in MySQL 2.23.24-beta. I
> wouldn't mind if it was a rounding issue but the value 666666.66 becomes
> 666666.69 and 777777.77 becomes 777777.75!
Sounds to me like a typical binary rounding issue - when you store decimal
values in a binary floating point value, the values are not rounded in
decimal as you would expect but in binary. For example, it is not possible
to denote 0.1 (ie, 10^-1) with binary floating point values. You will only
get the approximation
1/16+1/32+1/256+1/512+1/4096+1/8192+1/65536+1/131072+...
depending on how many bits you have available.
I believe that in MySQL the column type you want to use is
decimal(prec,scale) (if you know how many significant digits and digits
after the decimal point you need), because these are stored as strings in
the database, and thus no rounding occurs (until you use the values
somewhere else by transforming them into floating-point values that is :-).
--
Tomi Junnila <[EMAIL PROTECTED]>
http://www.badzilla.net/~topeju/
Electronics and Information Technology,
University of Turku, Finland
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