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At 03:31 PM 9/10/97 EDT, Hans wrote:

>Bob: There's nothing wrong with the implementation of null-capable
>fields in RPG. I have my concerns about the design, but the
>implementation is just fine!
>
>Actually, my concern with the design is that we did not go far enough
>in supporting the concept. (And perhaps someday, we'll provide a full
>support for null fields.)
>
>But I suspect that that's not what you are complaining about. Is it
>that you don't like the whole concept of what a null-capable field really
>is? As you know (or should know), the "nullness" of a field is not a
>value of the field, but rather, some sort of dynamic attribute of the
>field. It is an indication of the presence or absence of data within
>that field. That guided our design of %NULLIND in RPG. We did not
>want to "nullify" a null-capable field by allowing something like *NULL
>to be assigned to it. *NULL is a value, and not an attribute. %NULLIND
>emphasizes the point that nullness is an attribute, and is independent
>of the actual data.
>

Hans

This seems to me too fine a distinction. I understand what you're saying. However, in everyday usage, which is where I live, could not the nullness of a field be treated both ways? My example is SQL, where, on the one hand, NULL is a predidate, with usage like 'expression IS NULL'. On the other hand, NULL can be assigned to a column. There's even the statement 'All data types include the null value.'

I just think that NULL is more often handled as a value, although it is, technically speaking, an attribute.

MHO

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