Обсуждение: forcing a table (parent in inheritance) tor emain empty
Hey dear list,
I can't find a nice solution to enforce a necessary behaviour in my case :
I want a parent table to remain empty.
Of course I could define a trigger and return NULL in any case, but I'd like a more elegant approach using check or constraints.
Any thought appreciated,
Cheers,
Rémi C
On Tue, Oct 11, 2016 at 12:27 PM, Rémi Cura <remi.cura@gmail.com> wrote: > Hey dear list, > I can't find a nice solution to enforce a necessary behaviour in my case : > I want a parent table to remain empty. > > Of course I could define a trigger and return NULL in any case, but I'd like > a more elegant approach using check or constraints. You could probably do it with a simple constraint: postgres=# create table dum(check (false)); CREATE TABLE postgres=# insert into dum default values; ERROR: new row for relation "dum" violates check constraint "dum_check" DETAIL: Failing row contains ().
This solution is very nice.
Sadly the check is inherited by the children
(I only want the parent to be empty, not the children).
It seems the element that are not inherited are
- Indexes
- Unique constraints
- Primary Keys
- Foreign keys
- Rules and Triggers
thanks anyway for the fast answer,
Cheers,
Rémi C
2016-10-11 18:33 GMT+02:00 Manuel Gómez <targen@gmail.com>:
On Tue, Oct 11, 2016 at 12:27 PM, Rémi Cura <remi.cura@gmail.com> wrote:
> Hey dear list,
> I can't find a nice solution to enforce a necessary behaviour in my case :
> I want a parent table to remain empty.
>
> Of course I could define a trigger and return NULL in any case, but I'd like
> a more elegant approach using check or constraints.
You could probably do it with a simple constraint:
postgres=# create table dum(check (false));
CREATE TABLE
postgres=# insert into dum default values;
ERROR: new row for relation "dum" violates check constraint "dum_check"
DETAIL: Failing row contains ().
On 11/10/2016 19:04, Rémi Cura wrote: > This solution is very nice. > Sadly the check is inherited by the children > (I only want the parent to be empty, not the children). > > It seems the element that are not inherited are > > * Indexes > * Unique constraints > * Primary Keys > * Foreign keys > * Rules and Triggers > you can specify a "NO INHERIT" on the check constraint, that should solve your issue. -- Julien Rouhaud http://dalibo.com - http://dalibo.org
Perfect !
Cheers,
Rémi C
2016-10-11 19:12 GMT+02:00 Julien Rouhaud <julien.rouhaud@dalibo.com>:
On 11/10/2016 19:04, Rémi Cura wrote:
> This solution is very nice.
> Sadly the check is inherited by the children
> (I only want the parent to be empty, not the children).
>
> It seems the element that are not inherited are
>
> * Indexes
> * Unique constraints
> * Primary Keys
> * Foreign keys
> * Rules and Triggers
>
you can specify a "NO INHERIT" on the check constraint, that should
solve your issue.
--
Julien Rouhaud
http://dalibo.com - http://dalibo.org