Обсуждение: conditional alter table

I'd like to either 1) execute an alter table to re-add a constraint only
if it doesn't exist or 2) have psql ignore the failure when setting it's
exit status.  Any ideas on how to do either would be appreciated.

Posgres 8.1.2

Thanks,
Brian

Brian Cox wrote:
> I'd like to either 1) execute an alter table to re-add a constraint only
> if it doesn't exist or 2) have psql ignore the failure when setting it's
> exit status.  Any ideas on how to do either would be appreciated.

I don't think there's a way to do that but you can look at the
pg_constraint table to see if it exists.

http://www.postgresql.org/docs/current/static/catalog-pg-constraint.html
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