Maybe try something like this:
- Set an error handler
- Try to use that field or variable
- If it is null then the error handler will catch it

eg:
ON ERR CALL("errorcatcher")
$result:=$BooleanVarOrfield=true
ON ERR CALL("")

On 2 June 2018 at 15:02, Arnaud de Montard via 4D_Tech <4d_tech@lists.4d.com
> wrote:

>
> > Le 1 juin 2018 à 20:39, Chip Scheide via 4D_Tech <4d_tech@lists.4d.com>
> a écrit :
> >
> > I meant - I was looking for a command which behaved like Nil(), but for
> > Null.
>
> Hi Chip,
> I had a bad recent experience with a legacy db in which check box "convert
> Null to empty" was sometimes on, sometimes off… The use of QUERY command,
> in that situation, is risky:
>    //example with date
>  QUERY($table_p->;$field_p->=!00/00/0000!)
>  $empty_l:= Records in selection($table_p->)
>  QUERY($table_p->;$field_p->#!00/00/0000!)
>  $notEmpty_l:= Records in selection($table_p->)
>  ASSERT(Records in table($table_p->)=($empty_l+$notEmpty_l);"data
> integrity or bad Null setting")
>
> It's checked everywhere now.
>
> In a brand new DB, and *knowing what strategy has been adopted about Null
> use*, things could be different.
>
> --
> Arnaud de Montard
>
>
>
> **********************************************************************
> 4D Internet Users Group (4D iNUG)
> FAQ:  http://lists.4d.com/faqnug.html
> Archive:  http://lists.4d.com/archives.html
> Options: https://lists.4d.com/mailman/options/4d_tech
> Unsub:  mailto:4d_tech-unsubscr...@lists.4d.com
> **********************************************************************
>



-- 
*************************************************
CatBase - Top Dog in Data Publishing
tel: +44 (0) 207 118 7889
w: http://www.catbase.com
skype: pat.bensky
*************************************************
**********************************************************************
4D Internet Users Group (4D iNUG)
FAQ:  http://lists.4d.com/faqnug.html
Archive:  http://lists.4d.com/archives.html
Options: https://lists.4d.com/mailman/options/4d_tech
Unsub:  mailto:4d_tech-unsubscr...@lists.4d.com
**********************************************************************

Reply via email to