Question about Foreign key!

On Fri, Jul 27, 2001 at 04:33:24PM +0200, Fariba Noorbakhsh wrote:

Hi everybody,

Is there anyway to define foreign Key ,.. (constraints) after creating
table?
As far I know, you can't do it with ALTER table!!!

template1=# \h alter table
Command: ALTER TABLE
...
ALTER TABLE table
ADD table constraint definition
...

eg:
Table "tblPerson"
Attribute | Type | Modifier
---------------------------+--------------------------+----------
ID | integer |
...
Table "tblAddress"
Attribute | Type | Modifier
------------+--------------------------+----------
ID | integer |
PersonID | integer |
...

create unique index tblperson_pkey on "tblPerson"("ID");
alter table "tblAddress"
add constraint addfk
foreign key("PersonID") references "tblPerson"("ID") match full;

Hope this helps,

Patrick

Fariba Noorbakhsh wrote:

On Mon, Aug 06, 2001 at 05:42:09PM +0200, Fariba Noorbakhsh wrote:

Hi Patrick,

Do you know how I can drop(delete) a column from a table?! Just a column. I don't
think you can do it with Alter table

Thanks in advance,
Fariba

According to the TODO list:

COMMANDS
...
* ALTER
...
o Add ALTER TABLE DROP COLUMN feature [drop]

so the way forward may be to
pg_dump -t your_table -D your_database > table.txt
and have fun editing out all reference to said column from table.txt. Then
drop the table and reload from table.txt. YMMV..

Cheers,

Patrick

Another way SELECT INTO a new table, omitting the column you want to delete.

Tim

----- Original Message -----
From: "Patrick Welche" <prlw1@newn.cam.ac.uk>
To: "Fariba Noorbakhsh" <fNoorbakhsh@tecways.com>
Cc: <pgsql-general@postgresql.org>
Sent: Monday, August 13, 2001 7:36 AM
Subject: Re: [GENERAL] delete columns from table!

On Mon, Aug 06, 2001 at 05:42:09PM +0200, Fariba Noorbakhsh wrote:

Hi Patrick,

Do you know how I can drop(delete) a column from a table?! Just a

column. I don't

Another method is to create a new table with only the desired fields with
the SELECT INTO query

i.e. SELECT <desired query> INTO TABLE <new table> FROM <old table>

then, after deleting the old table, you will need to rename the new,
temporary table, to that of your old table. Your conditions will need to
be reset with the new table, as it will only contain data.

Hope that help

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Kevin Drewiske '01 CE
MSOE Webmaster Team: http://www.msoe.edu/
KJDesign Website Development: http://www.drewiske.com/KJDesign/
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

-----Original Message-----
From: Patrick Welche [SMTP:prlw1@newn.cam.ac.uk]
Sent: Monday, August 13, 2001 09:37
To: Fariba Noorbakhsh
Cc: pgsql-general@postgresql.org
Subject: Re: delete columns from table!

On Mon, Aug 06, 2001 at 05:42:09PM +0200, Fariba Noorbakhsh wrote:

Hi Patrick,

Do you know how I can drop(delete) a column from a table?! Just a column.

I don't

think you can do it with Alter table

Thanks in advance,
Fariba

According to the TODO list:

COMMANDS
...
* ALTER
...
o Add ALTER TABLE DROP COLUMN feature [drop]

so the way forward may be to
pg_dump -t your_table -D your_database > table.txt
and have fun editing out all reference to said column from table.txt. Then
drop the table and reload from table.txt. YMMV..

Cheers,

Patrick

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Thanks, it helps!

Tim Barnard wrote: