[Gambas-user] handling database nulls

[Werner]

Bruce wrote:
> This has sort of been asked before. However, the answers I have found haven't 
> helped.
>
> My database has a LOT of integer fields, arranged into sets of fieldwork 
> results.  The majority of them contain nulls, quite validly as the data for a 
> particular set may not have been entered or even collected yet.
>
> My Gambas problem is creating the classes for the various plot types.  Within 
> Gambas the data items are integers. When I try and read the existing datum 
> point into the class (as in dp.rangeheight=$dbresult!rangeheight ) it is 
> complaining that the value is a null not an integer, as in "wanted integer, 
> got null instead").
>
> Now, coercing the value of the object data to zero is NOT valid, as in the 
> above example, the rangeheight is null not zero, as zero means 0m above the 
> basepoint.  Similarly, coercing it to a negative value wont work either, as 
> that means meters below the base point.
>
> Is there any way to set the value of an integer variable to an "uninitalised" 
> state?
>
> bruce
>   
A solution might be to use the Variant data type instead of Integer.
Alternatively, you could define a class that holds a data point plus a
flag whether the data is valid.

Werner