On Thu, 2006-11-02 at 19:10 -0500, Matthew Terenzio wrote: > suppose you wanted to be certain that either one of two or more > columns were present > > Like in a user table, either a username or an email need to be present > to create a row. > > You can't use not null because it's an either or situation. > > what's the best method to accomplish this sort of constraint? See check constraints: http://www.postgresql.org/docs/8.1/interactive/ddl-constraints.html#AEN1954 I suppose you seek something like this: create table people ( name text, email text, constraint valid_name_or_email check (name is not null or email is not null) ); Cheers, Reece -- Reece Hart, http://harts.net/reece/, GPG:0x25EC91A0
