On 24-4-2017 20:50, Maxi maxirobaina@... [firebird-support] wrote:

>
>
> Hi everyone,
>
> I encountered strange behavior droping a column definition with default
> value.
>
> The environment is Ubuntu 16.04 LTS 64 bits, Firebird version
> LI-V2.5.6.27020 (Firebird 2.5 SuperClassic)
>
>
> I'll try to explain with an example. The statement sequence is:
>
> 1. Create the table
> CREATE TABLE "SCHEMA_AUTHOR" ("ID" integer NOT NULL PRIMARY KEY, "NAME"
> varchar(255) NOT NULL, "HEIGHT" integer CHECK ("HEIGHT" >= 0))
>
> 2. Popultate with some data
> INSERT INTO SCHEMA_AUTHOR (ID, NAME, HEIGHT) VALUES ('1', 'Anonimus1',
> NULL);
>
> 3. Alter the table
> ALTER TABLE "SCHEMA_AUTHOR" ADD "SURNAME" varchar(15) DEFAULT 'surname
> default' NOT NULL
>
> After step 3, I have a record with a new column with 'surname default'
> value into SURNAME field.
>
> 4. Drop default definition
> ALTER TABLE "SCHEMA_AUTHOR" ALTER COLUMN "SURNAME" DROP DEFAULT
>
> After step 4, the SURNAME field value is setting to empty string ('')
>
> Is that the correct behavior ?

Yes and no. Yes this is how Firebird works, and no it doesn't conform to
the behavior expected by the SQL standard. Firebird 3 does it better,
but some people consider that to be a bug (see CORE-5507 and the
accompanying discussion on firebird-devel).

Mark
--
Mark Rotteveel