Re: Alter Table Auto_Increment

On 20 September 2010 14:53, Carlos Mennens <carlos(dot)mennens(at)gmail(dot)com> wrote:
> I have a table in my database and would like to modify the one column
> that is already configured to be the PRIMARY KEY but I forgot to set
> it for AUTO_INCREMENT. For some reason I can't find what the proper
> command would be in the documentation and my commands from MySQL don't
> appear to work properly in PostgreSQL:
>
>
> sun=# \d blades
>            Table "public.blades"
>  Column  |         Type          | Modifiers
> ----------+-----------------------+-----------
>  id       | integer               | not null
>  ilom_ip  | character varying(15) |
>  host_os  | character varying(50) |
>  host_ip  | character varying(15) |
>  hostname | character varying(50) |
>  serial   | character varying(30) |
>  gfe      | character varying(10) |
>  admin    | character varying(50) |
> Indexes:
>    "blades_pkey" PRIMARY KEY, btree (id)
>
> My command is not working so I don't know what I am doing wrong:
>
> sun=# ALTER TABLE blades MODIFY int AUTO_INCREMENT;
> ERROR:  syntax error at or near "MODIFY"
> LINE 1: ALTER TABLE blades MODIFY int AUTO_INCREMENT;
>

That's MySQL syntax. Usually you'd just use the SERIAL datatype which
automatically creates a sequence. But since you've already made the
table, you can create it manually:

CREATE SEQUENCE seq_blades_id;
SELECT setval('seq_blades_id', max(id)) FROM blades; -- set the
sequence's value to the maximum value of "id"
ALTER TABLE blades ALTER COLUMN id SET DEFAULT
nextval('seq_blades_id'); -- make default value get value from
sequence

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Thom Brown
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