我已经更新了我的 NORMA 模型以更接近您的图表。我可以看到您在哪里犯了一些错误,但其中一些可能是由于我的早期模型造成的。
我已更新此模型以防止重复标签。以前真的无所谓。但既然你想要它,这里就是(对于 Postgres):
START TRANSACTION ISOLATION LEVEL SERIALIZABLE, READ WRITE;
CREATE SCHEMA so;
SET search_path TO SO,"$user",public;
CREATE DOMAIN so.HashedPassword AS
BIGINT CONSTRAINT HashedPassword_Unsigned_Chk CHECK (VALUE >= 0);
CREATE TABLE so."User"
(
USER_ID SERIAL NOT NULL,
USER_NAME CHARACTER VARYING(50) NOT NULL,
EMAIL_ADDRESS CHARACTER VARYING(256) NOT NULL,
HASHED_PASSWORD so.HashedPassword NOT NULL,
OPEN_ID CHARACTER VARYING(512),
A_MODERATOR BOOLEAN,
LOGGED_IN BOOLEAN,
HAS_BEEN_SENT_A_MODERATOR_MESSAGE BOOLEAN,
CONSTRAINT User_PK PRIMARY KEY(USER_ID)
);
CREATE TABLE so.Question
(
QUESTION_ID SERIAL NOT NULL,
TITLE CHARACTER VARYING(256) NOT NULL,
WAS_SENT_AT_TIME TIMESTAMP NOT NULL,
BODY CHARACTER VARYING NOT NULL,
USER_ID INTEGER NOT NULL,
FLAGGED_FOR_MODERATOR_REMOVAL BOOLEAN,
WAS_LAST_CHECKED_BY_MODERATOR_AT_TIME TIMESTAMP,
CONSTRAINT Question_PK PRIMARY KEY(QUESTION_ID)
);
CREATE TABLE so.Tag
(
TAG_ID SERIAL NOT NULL,
TAG_NAME CHARACTER VARYING(20) NOT NULL,
CONSTRAINT Tag_PK PRIMARY KEY(TAG_ID),
CONSTRAINT Tag_UC UNIQUE(TAG_NAME)
);
CREATE TABLE so.QuestionTaggedTag
(
QUESTION_ID INTEGER NOT NULL,
TAG_ID INTEGER NOT NULL,
CONSTRAINT QuestionTaggedTag_PK PRIMARY KEY(QUESTION_ID, TAG_ID)
);
CREATE TABLE so.Answer
(
ANSWER_ID SERIAL NOT NULL,
BODY CHARACTER VARYING NOT NULL,
USER_ID INTEGER NOT NULL,
QUESTION_ID INTEGER NOT NULL,
CONSTRAINT Answer_PK PRIMARY KEY(ANSWER_ID)
);
ALTER TABLE so.Question
ADD CONSTRAINT Question_FK FOREIGN KEY (USER_ID)
REFERENCES so."User" (USER_ID) ON DELETE RESTRICT ON UPDATE RESTRICT;
ALTER TABLE so.QuestionTaggedTag
ADD CONSTRAINT QuestionTaggedTag_FK1 FOREIGN KEY (QUESTION_ID)
REFERENCES so.Question (QUESTION_ID) ON DELETE RESTRICT ON UPDATE RESTRICT;
ALTER TABLE so.QuestionTaggedTag
ADD CONSTRAINT QuestionTaggedTag_FK2 FOREIGN KEY (TAG_ID)
REFERENCES so.Tag (TAG_ID) ON DELETE RESTRICT ON UPDATE RESTRICT;
ALTER TABLE so.Answer
ADD CONSTRAINT Answer_FK1 FOREIGN KEY (USER_ID)
REFERENCES so."User" (USER_ID) ON DELETE RESTRICT ON UPDATE RESTRICT;
ALTER TABLE so.Answer
ADD CONSTRAINT Answer_FK2 FOREIGN KEY (QUESTION_ID)
REFERENCES so.Question (QUESTION_ID) ON DELETE RESTRICT ON UPDATE RESTRICT;
COMMIT WORK;
请注意,现在有一个单独的标记表TAG_ID
作为主键。TAG_NAME
是一个单独的列,具有唯一性约束,防止重复标签。该QuestionTaggedTag
表现在具有 ( QUESTION_ID
, TAG_ID
),这也是它的主键。
我希望我在回答这个问题时不要走得太远,但是当我尝试写较小的答案时,我一直不得不解开我之前的答案,而且发布这个似乎更简单。