Обсуждение: Is Dropping a column "CHECK" constraint possible?

Hi Folks ,

can anyone please help?
i have a to drop a check contstraint from a column. eg

tradein_clients=# \d t_a          Table "t_a"  Column   |  Type   | Modifiers
------------+---------+-----------company_id | integer |exp        | text    |imp        | text    |
Check constraints: "$1" (length(imp) > 1)                  "aaaaaq" (length(imp) > 1)

Can i remove to contraints thru ALTER TABLE or similar commands.
I have read the docs for ALTER TABLE but the command described is
not working for me.

=======================================================
ALTER TABLE [ ONLY ] table       DROP CONSTRAINT constraint { RESTRICT | CASCADE }
========================================================

Regards
Mallah.

--
Rajesh Kumar Mallah,
Project Manager (Development)
Infocom Network Limited, New Delhi
phone: +91(11)6152172 (221) (L) ,9811255597 (M)

Visit http://www.trade-india.com ,
India's Leading B2B eMarketplace.

> can anyone please help?
> i have a to drop a check contstraint from a column. eg
> 
> tradein_clients=# \d t_a
>            Table "t_a"
>    Column   |  Type   | Modifiers
> ------------+---------+-----------
>  company_id | integer |
>  exp        | text    |
>  imp        | text    |
> Check constraints: "$1" (length(imp) > 1)
>                    "aaaaaq" (length(imp) > 1)
> 
> Can i remove to contraints thru ALTER TABLE or similar commands.
> I have read the docs for ALTER TABLE but the command described is 
> not working for me.

This should work, so long as you're using postgres 7.2+

ALTER TABLE "t_a" DROP CONSTRAINT "aaaaaq" RESTRICT;

Chris

Yup it did!.
Thanks a ton,

it was there in the ALTER TABLE documentation
i overlooked :-(

regds
mallah.





On Saturday 06 July 2002 10:05, Christopher Kings-Lynne wrote:
> > can anyone please help?
> > i have a to drop a check contstraint from a column. eg
> >
> > tradein_clients=# \d t_a
> >            Table "t_a"
> >    Column   |  Type   | Modifiers
> > ------------+---------+-----------
> >  company_id | integer |
> >  exp        | text    |
> >  imp        | text    |
> > Check constraints: "$1" (length(imp) > 1)
> >                    "aaaaaq" (length(imp) > 1)
> >
> > Can i remove to contraints thru ALTER TABLE or similar commands.
> > I have read the docs for ALTER TABLE but the command described is
> > not working for me.
>
> This should work, so long as you're using postgres 7.2+
>
> ALTER TABLE "t_a" DROP CONSTRAINT "aaaaaq" RESTRICT;
>
> Chris

--
Rajesh Kumar Mallah,
Project Manager (Development)
Infocom Network Limited, New Delhi
phone: +91(11)6152172 (221) (L) ,9811255597 (M)

Visit http://www.trade-india.com ,
India's Leading B2B eMarketplace.

Hi ,

i want to enforce that a coulumn 'imp'
shud either contain valid data or no data at all.

by valid data i mean data having at least one non whitespace character.

will this constraint be approprote for accomplishing it?

tradein_client=>  ALTER TABLE t_a ADD   CHECK ( length(  btrim(imp) ) > 1 or imp is NULL );

regards
mallah.




On Saturday 06 July 2002 10:05, Christopher Kings-Lynne wrote:
> > can anyone please help?
> > i have a to drop a check contstraint from a column. eg
> >
> > tradein_clients=# \d t_a
> >            Table "t_a"
> >    Column   |  Type   | Modifiers
> > ------------+---------+-----------
> >  company_id | integer |
> >  exp        | text    |
> >  imp        | text    |
> > Check constraints: "$1" (length(imp) > 1)
> >                    "aaaaaq" (length(imp) > 1)
> >