Обсуждение: How to setup a column constraint for an integer type? Default 0 if not defined

Hi,


I'm trying to port some source code to Postgres 8.3.8 and have been encountering some surprises :-(
I would like to set up a column constraint for an integer type, so that when the value is undefined, it would assign a
defaultvalue of 0 to that column. 
How would I do that in 8.3.8?  Please provide an example.

Mary

Wang, Mary Y wrote:
> Hi,
>
>
> I'm trying to port some source code to Postgres 8.3.8 and have been encountering some surprises :-(
> I would like to set up a column constraint for an integer type, so that when the value is undefined, it would assign
adefault value of 0 to that column. 
> How would I do that in 8.3.8?  Please provide an example.
>

when you say, 'value is undefined' do you mean, if an insert is done
without specifying that field ?

in that case, ou wouldn't use a constraint, you'd use a DEFAULT value,
like...

    CREATE TABLE tblname (
                   ....
                  somefield INTEGER DEFAULT 0,
                   ....
                   );

or, if the table already exists...

    ALTER TABLE tblname ALTER COLUMN somefield SET DEFAULT 0;