postgresql unique constraint not unique enough - postgresql

Question

I am creating tables to handle the security question/selected question/given answer section of our database and getting this error:
there is no unique constraint matching given keys for referenced table "m_security_questions"
Not sure how I fix this?
(Since schema won't build b/c of error, I couldn't add SQL Fiddle)
CREATE TABLE security_question --defines questions
(
id SERIAL PRIMARY KEY NOT NULL,
question character varying(1024) NOT NULL,
is_custom boolean DEFAULT FALSE NOT NULL
);
INSERT INTO security_question
(question,is_custom)
VALUES
('do you know the answer?',FALSE),
('Write your own question',TRUE);
CREATE TABLE m_security_questions
( --defines question a member chooses & allows free form question
-- id SERIAL NOT NULL,
-- I know adding id like this and making keeping same pk solves it
-- but isn't storing the extra sequence not needed?
member integer --REFERENCES member(m_no)
-- commented out reference for so only
NOT NULL,
question integer REFERENCES security_question(id) NOT NULL,
m_note text,
PRIMARY KEY(member,question)
);
-- here I add unique constraint but doesn't the primary already mean I have a unique index?
ALTER TABLE m_security_questions ADD CONSTRAINT m_security_questions_unique_member_question UNIQUE (member,question);
INSERT INTO m_security_questions
(member,question,m_note)
VALUES
(2,1,NULL),
(2,2,'How many marbles in this jar?');
CREATE TABLE m_security_answer --defines members given answer
( -- I want member & question here to line up w/ same from m_security_questions
member integer REFERENCES m_security_questions(member),
question integer REFERENCES m_security_questions(question) NOT NULL,
answer character varying(255) NOT NULL,
PRIMARY KEY (member,question)
);
-- here is where I get the error:
-- there is no unique constraint matching given keys for referenced table "m_security_questions"
INSERT INTO m_security_answer
(member,question,answer)
VALUES
(2,1,'yes'),
(2,2,'431');

Answer 1

The primary key definitely defines a unique constraint. But the unique constraint is on (member,question). Your have two FOREIGN KEY constraints that references just (member) and (question) separately.
I'm pretty sure what you want is:
CREATE TABLE m_security_answer --defines members given answer
(
member integer,
question integer NOT NULL,
answer character varying(255) NOT NULL,
PRIMARY KEY (member,question),
FOREIGN KEY (member, question) REFERENCES m_security_questions(member, question)
);