[GRASS-user] Entering '<1' and 'BDL' in Database

[Dylan Beaudette]

On Monday 19 April 2010, Rich Shepard wrote:
> On Mon, 19 Apr 2010, Dylan Beaudette wrote:
> > how about NULL ?
>
> Dylan,
>
>    NULL means unknown, and 'less than 1' or 'below detection limits' means
> it cannot be measured with the instruments used. There's a big difference.
> NULL can result from the measurement not being taken or the analysis not
> being conducted.
>
> Thanks,
>
> Rich

Hi,

In that case, how about another column that contains quality control 
information. There isn't really any mechanism in most relational database 
models that would allow you to store 'mixed' datatypes AND interpret them as 
a numeric datatype... to the best of my knowledge. 

Cheers,
Dylan



-- 
Dylan Beaudette
Soil Resource Laboratory
http://casoilresource.lawr.ucdavis.edu/
University of California at Davis
530.754.7341