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.
