Thread: Question about Foreign key!
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!!! Thanks in advance, Fariba
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: > 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
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 > > 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 > > ---------------------------(end of broadcast)--------------------------- > TIP 1: subscribe and unsubscribe commands go to majordomo@postgresql.org >
Thanks, it helps! Tim Barnard wrote: > 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 > > > 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 > > > > ---------------------------(end of broadcast)--------------------------- > > TIP 1: subscribe and unsubscribe commands go to majordomo@postgresql.org > > > > ---------------------------(end of broadcast)--------------------------- > TIP 5: Have you checked our extensive FAQ? > > http://www.postgresql.org/users-lounge/docs/faq.html