postgresql唯一約束不夠獨特

Question

我正在創建表來處理我們數據庫的安全問題/選定問題/給定答案部分並收到此錯誤：

對於引用表“m_security_questions”的給定鍵，沒有唯一約束匹配

不確定我是怎么解決的？

（由於架構不會構建錯誤的b / c，我無法添加SQL小提琴）

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

主鍵肯定定義了唯一約束。 但唯一的約束是（成員，問題）。 您有兩個FOREIGN KEY約束，分別引用（成員）和（問題）。

我很確定你想要的是：

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)
  );