Re: alter table

On Wed, 15 Feb 2006, Owen Jacobson wrote:

> Maciej Piekielniak wrote:
> >
> > Wednesday, February 15, 2006, 8:31:17 PM, you wrote:
> > OJ> Note that prior to 8.0 PostgreSQL does not support
> > multiple ALTER actions in a single query.  To get an
> > equivalent effect, wrap separate ALTER TABLE queries in a transaction:
> >
> > OJ> BEGIN;
> > OJ> alter table xyz alter column id set default nextval('xyz_seq');
> > OJ> alter table xyz alter column foo set default '';
> > OJ> COMMIT;
> > OJ> Also, are you sure you want '' as a column default, and
> > not ALTER COLUMN foo DROP DEFAULT?
> > OJ> -Owen
> >
> > OK. THX. Second question:
> >
> > First, maybe set many fields with the same action - ex. set default?
> >
> > Ex. on mysql
> >
> > ALTER TABLE proc MODIFY name char(64) DEFAULT '' NOT NULL,
> >                  MODIFY specific_name char(64) DEFAULT '' NOT NULL,
> >                  MODIFY sql_data_access
> >                         enum('CONTAINS_SQL',
> >                              'NO_SQL',
> >                              'READS_SQL_DATA',
> >                              'MODIFIES_SQL_DATA'
> >                             ) DEFAULT 'CONTAINS_SQL' NOT NULL....
>
> Under PostgreSQL 7.4 you'd need to do those as three separate ALTER TABLE statements:
>
> BEGIN;
> ALTER TABLE proc ALTER name DEFAULT '' NOT NULL;
> ALTER TABLE proc ALTER specific_name DEFAULT '' NOT NULL;
> ... and so on ...
> COMMIT;
>
> Note that ALTER TABLE under postgresql cannot change a column's type
> (including precision or length).

Not in 7.4, but I believe 8.1 allows that (ALTER TABLE ALTER COLUMN TYPE
with semi-optional USING)