Re: Multi-table CHECK constraint

Richard Broersma wrote:
> On Wed, Dec 10, 2008 at 3:58 PM, Jason Long
> <mailing(dot)list(at)supernovasoftware(dot)com> wrote:
>
>
>> I need to add some complex constraints at the DB.
>> These will involve several tables.
>> What is the best approach for this?
>>
>
> Well ANSI-SQL provides the CREATE ASSERTION for this purpose.
> However, PostgreSQL doesn't support this feature. It can be mimiced
> by using the PostgreSQL CONSTRAINT TRIGGER extenstion. IIRC, it works
> very much like an ordinary trigger except that you must raise an error
> when an DML attempt possibly violates your condition.
>
>
>> Can someone point me to an example of doing something like this?
>>
>
> http://www.postgresql.org/docs/8.3/interactive/sql-createconstraint.html
> http://www.postgresql.org/docs/8.3/interactive/triggers.html
>
> I hope this helps.
>
>
>
Thanks. I will look into this and see how it goes.

Any other advice would be greatly appreciated.