NULL indicator in Variant

[Steve Teale]

> Any reason making a custom NULL type wouldn't work? i.e:
> 
> struct NULL {}
> 
> Variant var = NULL;
> 
> assert(var.type == typeof(NULL));

I don't think that is any improvement on hasValue(). It would tell you 
the particular value was null, but would not tell you what type it was. 
In a typical situation you need to tell the database server the type of 
the parameter, even if it is null.

Steve