[DB-SIG] dBase III and VFP tables

Ethan Furman ethan at stoneleaf.us
Wed Jul 20 03:41:26 CEST 2011

Carl Karsten wrote:
> for those of you that are wondering about this nuttyness:  VFP is a
> dBase derivative.  In there early days, there was no support for Null.
>  But a side effect of adding a row but not storing values to it was
> empty fields.  the best example is a date.  dates are stored on disk
> as a string "YYYYMMDD"  and in the case of an empty date: "        ".
> Same with numbers: N(6,2) would store 3.14 as "  3.14" and an empty
> number was "      ".  Then they added Null support, but instead of
> using this empty state, they added a flag, so now a field could be
> Null, Blank or have a value.  which was a mistake, but here we are.

Thanks for the clarification, Carl.

> For D/T I am not sure you have a choice.  What value would you return
> for an empty date other than Null?

As it happens, I created custom Date, Time, and DateTime objects so that 
I could deal with the empty values.  I probably just should have 
returned None from the beginning, but did I mention that this is the 
project I have learned Python with?

Now that I have them, I'm thinking of keeping and continuing to use them 
for the empty case... but not sure if that's a great idea, hence my 
question here.

> for Logical I would return False.  Mainly because I am pretty sure
> that because in VFP an empty logical will be treated as .f. anywhere a
> logical is evaluated.

The test I tried before I left work seems to confirm that (it was just 


More information about the DB-SIG mailing list