Thanks, Helen.

That's exactly what I needed to know...


Kurt.
----------------------------------------
Never underestimate the Power of Denial.

>
>From: Helen Borrie <helebor@...>
>To: firebird-support@yahoogroups.com
>Sent: Tue, September 21, 2010 6:52:46 PM
>Subject: Re: [firebird-support] Float v. Double
>
>
>At 12:32 PM 22/09/2010, you wrote:
>>If I need to alter a table field from float to double,
>>does the data get converted at the time of the alter
>
>No...but the FLOAT values are compatible with the new data type of the column.
>
>>or do I need to export/import the data to get the correct values?
>
>For some type alterations you would need to, but for this one, no, there is
>nothing more to do.
>
>
>Be aware, though, of the unreliability of the existing data, compared to any new
>data that is stored after the type change. When it was stored as FLOAT, you had
>9 digits of precision of which (at most) 7 would be reliable. There is no way
>to "squeeze" more exactness from the same data, i.e., no casting or calculation
>that would enhance the exactness to ~ 15 digits that you would expect with data
>stored to the same columns as DOUBLE PRECISION. So those older data will remain
>roughly as [in]accurate as they always were.
>
>./heLen
>
>
>

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