> My question therefore is, is it possible to create a foreign key that is
> conditional, i.e. only enforce the foreign key where the value in that
> table is not null.
My understanding from reading previous threads on this topic is the answer
is no, however you could make your own pseudo-foreign key using triggers to
do the same job, but only when your column is not null.
Not sure of the performance impact of doing this though - someone else may
be able to advise pros and cons in more detail.
Cheers,
~p
THINK BEFORE YOU PRINT - Save paper if you don't really need to print this
*******************Confidentiality and Privilege Notice*******************
The material contained in this message is privileged and confidential to
the addressee. If you are not the addressee indicated in this message or
responsible for delivery of the message to such person, you may not copy
or deliver this message to anyone, and you should destroy it and kindly
notify the sender by reply email.
Information in this message that does not relate to the official business
of Weatherbeeta must be treated as neither given nor endorsed by Weatherbeeta.
Weatherbeeta, its employees, contractors or associates shall not be liable
for direct, indirect or consequential loss arising from transmission of this
message or any attachments
e-mail.
---------------------------(end of broadcast)---------------------------
TIP 7: You can help support the PostgreSQL project by donating at
http://www.postgresql.org/about/donate
