On 25-Mar-2003 Black, Kelly W [PCS] wrote:
>
> On 25-Mar-2003 Black, Kelly W [PCS] wrote:
>>> Hello.
>>>
>>> Sorry for the long post. This has been a big problem for me, and I
>>> hope someone will help...
>>>
>>> I have a long standing problem with an MySQL query.
>>> Or perhaps a couple of sql query problems...
>>>
>>> Firstly I have been told I cannot use sum() on a value while using
>>> group by "parm" because it's not accurate. This is obvious as the
>>> result sets are often quite wrong...
>>>
>
>>I'm not sure where you got that. I've never seen it.
>
>
> See attached screen shot. It's common knowledge that when comparing
> six or eight there's no problem. But once you move into the millions
> there's quite a margin for error.
>
>
mysql> select 3333.33333334455 * 94343473264278464 as test;
+-----------------------------------+
| test |
+-----------------------------------+
| 314478244215319756800.00000000000 |
+-----------------------------------+
1 row in set (0.00 sec)
Since you'll only get 15 significant digits w/ a 64bit float, you're in
for considerable margins of error.
MySQL is _NOT_ an arbitrary precision calculator.
If you need that kind of precision, you should be working with DECIMAL().
Regards,
--
Don Read [EMAIL PROTECTED]
-- It's always darkest before the dawn. So if you are going to
steal the neighbor's newspaper, that's the time to do it.
(53kr33t w0rdz: sql table query)
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