On Wed, Mar 22, 2017 at 9:54 AM, Glen Huang <hey....@gmail.com> wrote:
> Hello, > > If I have a table like > > CREATE TABLE relationship ( > obj1 INTEGER NOT NULL REFERENCES object, > obj2 INTEGER NOT NULL REFERENCES object, > obj3 INTEGER NOT NULL REFERENCES object, > ... > ) > > And I want to constrain that if 1,2,3 is already in the table, rows like > 1,3,2 or 2,1,3 shouldn't be allowed. > > Is there a general solution to this problem? > > Sorry if the question is too basic, but I couldn't find the answer in the > doc, at least not in the chapter on unique index. > The most direct option to consider is a exclusion constraint. https://www.postgresql.org/docs/current/static/ddl-constraints.html (bottom of page) David J.
