Re: primary key and insert

Marc Fromm wrote:
> I created this table:
> ...
> id | integer | not null
> Indexes:
> "alert_list_pkey" PRIMARY KEY, btree (id)
> I get this error when I run the insert a listed below. The insert does
> not have an entry for the primary key "id" since I thought it updates
> automatically:
> *Warning*: pg_query() [function.pg-query
> <http://finaid46.finaid.wwu.edu/lan/student_alerts/function.pg-query>]:
> Query failed: ERROR: null value in column "id" violates not-null
> constraint
> ...
> How do I do an insert on this table and have the primary key "id"
> update with the record?
>
I think you are confusing primary key and serial.

A column can be a primary key (not-null, unique row id) or a serial
(actually automatically creates an integer type, a sequence, and a
default for the column of nextval('sequence') to automatically generate
a new value for each record).

A primary key could be a serial, but doesn't have to be.

A serial can be a primary key but doesn't have to be.

Note: due to things like transaction rollbacks, a serial column will
have unique IDs generated but they are not guaranteed to be consecutive.

Cheers,
Steve