W dniu 28.02.2016 o 03:35, David G. Johnston pisze: > W dniu 23.02.2016 o 09:39, Rafal Pietrak pisze: > > Can anybody suggest any other way out of this mass? > > > The only thought that sticks while reading your prose is: > > message ----> message-person <---- person > > > message-person (message_id, person_id, relationship_type[sender, > receiver]) It just occured to me: how do I make sure (e.g. force within a database) with the above structure, that a message can have *only one* sender? but, allow for multiple recepients? -R ____________________________________________________________________________________ If I'm not too late, unique partial index: CREATE UNIQUE INDEX unique_message_sender (message_id, person_id) WHERE relationship_type = sender; Regards, Igor -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
