Re: Is derby sql "real" equivalent to java "float"

["Dag H. Wanvik" <Da...@Sun.COM>]

Jim Newsham <jn...@referentia.com> writes:

> In the meantime, I'd like to ask.  Should Java float always be safely
> settable to a field of Derby type REAL?  This has been my assumption all
> along, and refderby.pdf seems to imply this.  Or, are there edge cases, such
> as perhaps NaN which will cause the set operation to fail.

The limits I mentioned in a previous post are actually documented:

Quote from http://db.apache.org/derby/docs/dev/ref/rrefsqlj14122.html

> REAL value ranges:
> 
>     * Smallest REAL value: -3.402E+38
>     * Largest REAL value: 3.402E+38
>     * Smallest positive REAL value: 1.175E-37
>     * Largest negative REAL value: -1.175E-37
> 
> These limits are different from the java.lang.Float Java type limits.
> 
> An exception is thrown when any double value is calculated or
> entered that is outside of these value ranges.

Thanks,
Dag

RE: Is derby sql "real" equivalent to java "float"

[Jim Newsham <jn...@referentia.com>]

Thanks for the pointer.  It turns out I overlooked this documentation.  I
was reading the pdf file, and only saw the overview of the data types, and
the assignability matrix.  

I guess I'll have to test my values for legal range before inserting into
the database.  It's unfortunate that there's a type range mismatch, though,
as it introduces an additional, potential cause of failure which I suspect
in most cases will not be expected or handled.  If there is no longer a good
reason for the mismatch, I too vote that it be removed.

Thanks,
Jim

> -----Original Message-----
> From: Dag.Wanvik@Sun.COM [mailto:Dag.Wanvik@Sun.COM]
> Sent: Wednesday, October 31, 2007 1:32 PM
> To: Derby Discussion
> Subject: Re: Is derby sql "real" equivalent to java "float"
> 
> Jim Newsham <jn...@referentia.com> writes:
> 
> > In the meantime, I'd like to ask.  Should Java float always be safely
> > settable to a field of Derby type REAL?  This has been my assumption all
> > along, and refderby.pdf seems to imply this.  Or, are there edge cases,
> such
> > as perhaps NaN which will cause the set operation to fail.
> 
> The limits I mentioned in a previous post are actually documented:
> 
> Quote from http://db.apache.org/derby/docs/dev/ref/rrefsqlj14122.html
> 
> > REAL value ranges:
> >
> >     * Smallest REAL value: -3.402E+38
> >     * Largest REAL value: 3.402E+38
> >     * Smallest positive REAL value: 1.175E-37
> >     * Largest negative REAL value: -1.175E-37
> >
> > These limits are different from the java.lang.Float Java type limits.
> >
> > An exception is thrown when any double value is calculated or
> > entered that is outside of these value ranges.
> 
> Thanks,
> Dag