Adding an one-out-of-two not null constraint in postgresql

Question

If I have a table in Postgresql:

create table Education ( 
    id                  integer references Profiles(id),
    finished            YearValue not nul         


        

Answer 1

You can also use a trigger on update and insert to check that a rule is followed before allowing the data into the table. You would normally use this type of approach when the check constraint needs more complicated logic.