Обсуждение: how to add primary key to existing table with multiple primary keys

On Thu, 23 Feb 2006, Daniel Joo wrote:

> I am trying to add another primary key to an existing table with two
> other primary keys.  I got the following error when I tried this
> command:

You only can have one primary key.  The table you gave has a single
primary key with two columns.  Are you trying to guarantee that expid
along is unique or that the set (probeid, tissueid, expid) is unique?

You can make expid UNIQUE and NOT NULL for the first case which is similar
to a primary key (although it's not a default foreign key target).  In the
second you can drop the current constraint and add one on the three
columns.

> Indexes:
>
>     "extprobe2tissue_pkey" PRIMARY KEY, btree (probeid, tissueid)
>     "extprobe2tissue_probeid" btree (probeid)
>     "extprobe2tissue_tissueid" btree (tissueid)

-----Mensaje original-----
De: pgsql-sql-owner@postgresql.org [mailto:pgsql-sql-owner@postgresql.org]En nombre de Daniel Joo
Enviado el: viernes, 24 febrero, 2006 2:45
Para: pgsql-sql@postgresql.org
Asunto: [SQL] how to add primary key to existing table with multiple primary keys

Hi there,

 

I am trying to add another primary key to an existing table with two other primary keys.  I got the following error when I tried this command:

 

alter table extprobe2tissue ADD primary key (expid);

ERROR:  multiple primary keys for table "extprobe2tissue" are not allowed

 

The details of the extprobe2tissue table is:

 

\d extprobe2tissue;

          Table "public.extprobe2tissue"

   Column    |          Type          | Modifiers

-------------+------------------------+-----------

 probeid     | integer                | not null

 tissueid    | integer                | not null

 value       | double precision       | not null

 entrydate   | date                   | not null

 description | character varying(200) |

 qval        | double precision       |

 expid       | integer                | not null

Indexes:

    "extprobe2tissue_pkey" PRIMARY KEY, btree (probeid, tissueid)

    "extprobe2tissue_probeid" btree (probeid)

    "extprobe2tissue_tissueid" btree (tissueid)

Foreign-key constraints:

    "extprobe2tissue_tissueid_fkey" FOREIGN KEY (tissueid) REFERENCES tissue(tissueid)

    "extprobe2tissue_probeid_fkey" FOREIGN KEY (probeid) REFERENCES extprobe(probeid)

 

Any suggestion would be much appreciated.

 

Thanks!