Re: Default column value

On 12/30/2016 06:46 AM, Adrian Klaver wrote:
> On 12/30/2016 06:38 AM, Rich Shepard wrote:

> test=> \d default_test
> Table "public.default_test"
> Column | Type | Modifiers
> --------+-------------------+-----------
> id | integer |
> fld_1 | character varying |
>
>>

To further illustrate this, NULL means UNKNOWN, not DEFAULT. Using
Adrian's example:

postgres=# create table default_test(id int, fld_1 varchar DEFAULT NULL);
CREATE TABLE
postgres=# INSERT into default_test VALUES(1,NULL);
INSERT 0 1
postgres=# INSERT into default_test VALUES(1,DEFAULT);
INSERT 0 1
postgres=# select * from default_test ;
id | fld_1
----+-------
1 |
1 |
(2 rows)

postgres=# alter table default_test alter column fld_1 set default now();
ALTER TABLE
postgres=# INSERT into default_test VALUES(1,DEFAULT);
INSERT 0 1
postgres=# INSERT into default_test VALUES(1,NULL);
INSERT 0 1
postgres=# select * from default_test ;
id | fld_1
----+-------------------------------
1 |
1 |
1 | 2016-12-30 09:11:11.170948-08
1 |
(4 rows)

Sincerely,

JD

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