Hi,

I have to select objects which are logically the same entities but come
from two different tables (not my model...). Some fields are only
available in either one of the sources.

The logic is already programmed but the database was now extended and I
want to create a view (select... tab1 union select... tab2) to keep as
much of the logic as possible. I can use any literal value to fill up
the non-existing columns, but to me it seemed to be the cleanest to use
NULLs.

Anyway, the Cast('' as Integer) worked...

But I am still curious why my Select and Create View both work but the
select on the view fails...

Regards

Michael

bozon wrote:
> Is there a reason for a view with a null column? I am curious how this
> could be useful?
>
> You could do this in your select :
>
> select
> case when 't'::boolean then null::integer end a,
> id
> from
> test
> ;
>
> I also wrote a procedure called null() that always returned null. I
> don't know what kind of performance hit that takes versus the above or
> the view.
>
>
> Michael Wimmer wrote:
>> Doug Lawry wrote:
>>> I can't reproduce this on 9.20.F, 9.30.UC7 or 9.40.FC1, so I'm not convinced the
>>> problem isn't elsewhere. However, try '':INTEGER as an alternative both to NULL
>>> and CAST.
>> Hi Doug,
>>
>> thanks a lot, '' did the trick.
>>
>> create view niltab (a)
>> as select cast('' as INTEGER),
>> from informix.systables
>>
>> Funny that you can not reproduce the problem. Did you try to create a
>> view and select from the view? Only the select on the view fails,
>> selecting from a table and creating the view works...
>>
>> If I change the '' to NULL inside the cast function, the select on the
>> view fails....
>>
>> Regards,
>>
>> Michael
>