Re: [GENERAL] Default column value

On 12/30/2016 06:38 AM, Rich Shepard wrote:
>   Reading the 9.6 docs suggests an answer to my question, but does not
> explicitly answer it, so I ask here.
>
>   If a column has a default value specified does this mean the column
> cannot
> contain a NULL value? In other words, is DEFAULT <some_value> NOT NULL
> redundant?

Another way of looking at it:

test=> create table default_test_2(id int, fld_1 varchar DEFAULT 'test');
CREATE TABLE

test=> insert into default_test_2 values (1);
INSERT 0 1

test=> insert into default_test_2 values (2, NULL);
INSERT 0 1

test=> \pset
null                     'NULL'

test=> select * from default_test_2 ;
 id | fld_1
----+-------
  1 | test
  2 | NULL
(2 rows)


DEFAULT is what is the column is set to if the user does not specify a value.
As shown above a user can supply a NULL value. To guard against that the NOT NULL
constraint is required.

>
> TIA,
>
> Rich
>
>


--
Adrian Klaver
adrian.klaver@aklaver.com