Subject | Re: [firebird-support] seems bug : Field accepts NULL Values (empty string) even if it is defined with not null constraints ?? |
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Author | Daniel Rail |
Post date | 2004-03-16T12:40:53Z |
Hi,
At March 16, 2004, 07:06, Jonathan Neve wrote:
field is NULL. Those methods are designed to return a valid value for
the type that is asked. And you would get NULL if you do
TField.AsVariant, because in Delphi NULL is of type variant. And, I
can find other such examples for other datatypes in Delphi, where a
NULL value can be misrepresented if using the specific assign
methods(i.e.: TField.AsDateTime = '30/12/1899', if the field value is
NULL).
--
Best regards,
Daniel Rail
Senior System Engineer
ACCRA Group Inc. (www.accra.ca)
ACCRA Med Software Inc. (www.filopto.com)
At March 16, 2004, 07:06, Jonathan Neve wrote:
> The main thing is that it leads to much confusion, and that I can'tThe same can be said of TField.AsInteger. It will return zero if the
> think of any situation where this subtle distinction would be useful. In
> fact, if you look at TField.AsString (in Delphi), it returns '' if the
> field is null. That's because Delphi doesn't have this subtle
> distinction (of course). In practice, why make this distinction?
field is NULL. Those methods are designed to return a valid value for
the type that is asked. And you would get NULL if you do
TField.AsVariant, because in Delphi NULL is of type variant. And, I
can find other such examples for other datatypes in Delphi, where a
NULL value can be misrepresented if using the specific assign
methods(i.e.: TField.AsDateTime = '30/12/1899', if the field value is
NULL).
--
Best regards,
Daniel Rail
Senior System Engineer
ACCRA Group Inc. (www.accra.ca)
ACCRA Med Software Inc. (www.filopto.com)