Joshua Tolley <eggyknap@gmail.com> writes:
> Primary keys are NOT NULL and UNIQUE. You can't have null values in a primary
> key.
On reflection I think the OP's beef is that we complain about this:
regression=# create table t (f1 int null not null);
ERROR: conflicting NULL/NOT NULL declarations for column "f1" of table "t"
but not this:
regression=# create table t (f1 int null primary key);
NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "t_pkey" for table "t"
CREATE TABLE
even though the implied NOT NULL is really a conflict. I think we could
fix that case if we cared to. However, since the NULL clause is
forgotten about after parsing, there isn't anything we could do to raise
a complaint about doing it in two steps:
regression=# create table t (f1 int null);
CREATE TABLE
regression=# alter table t add primary key(f1);
NOTICE: ALTER TABLE / ADD PRIMARY KEY will create implicit index "t_pkey" for table "t"
ALTER TABLE
(barring remembering the NULL clause in the catalogs, which seems
entirely silly). So I'm not sure how interesting it is to complain
about the single-command case.
regards, tom lane