Обсуждение: 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

On Thursday 11 December 2008 03:27:59 pm Marc Fromm wrote:
>  id         | integer                       | not null

I believe you did not set the field 'id' to a data type of serial.  If you had
you would have "nextval(" in the Modifiers column.

--
John Fabiani

I created this table:

   Column   |          Type                   | Modifiers
    ------------+------------------------+------------------------
   first_name | character varying(20)  |
  last_name  | character varying(30)  |
 w_number   | character varying(9)    | 
      alert      | character varying(200) | 
  post_date  | date                           |
       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]: Query failed: ERROR: null value in column "id" violates not-null constraint

$sql = "INSERT INTO alert_list (
                      w_number,
                      first_name,
                      last_name,
                      alert,
                      post_date
                  )
                  VALUES (
                      '$txtStudentNumber',
                      '$txtStudentFirstName',
                      '$txtStudentLastName',
                      '$txtStudentAlert',
                      'now()'
                  )";

How do I do an insert on this table and have the primary key "id" update with the record?

thanks

Marc