Question

我这里有4张桌子：

CREATE TABLE paper (
id VARCHAR(20) PRIMARY KEY,
name VARCHAR(30)
) ENGINE =INNODB;

CREATE TABLE subscriber (
id VARCHAR(10) PRIMARY KEY,
name VARCHAR(20),
address VARCHAR(30),
suburb VARCHAR(20),
state VARCHAR(3),
postcode VARCHAR(4))
round_id INTEGER NOT NULL,
FOREIGN KEY (round_id) REFERENCES round (id)
   ON UPDATE CASCADE ON DELETE RESTRICT
) ENGINE = INNODB;

CREATE TABLE current_order (
paper_id VARCHAR(20),
subscriber_id VARCHAR(10),
PRIMARY KEY (paper_id, subscriber_id),
FOREIGN KEY (paper_id) REFERENCES paper (id)
   ON UPDATE CASCADE ON DELETE RESTRICT,
FOREIGN KEY(subscriber_id) REFERENCES subscriber (id)
   ON UPDATE CASCADE ON DELETE RESTRICT)
ENGINE = INNODB;

CREATE TABLE receipt (
id INTEGER PRIMARY KEY AUTO_INCREMENT,
receipt_date DATE,
paid_till_date DATE,
paper_id VARCHAR(20),
subscriber_id VARCHAR(10))
ENGINE = INNODB;

现在表纸有一个主键ID，它由表current_order中的paper_id引用。表订户具有主键ID，它由表current_order中的subscriber_id引用。 Tabe current_order具有复合主键（paper_id，subscriber_id）。所以这三个表通过外键关系链接在一起。

如果我想将最后一张桌子收据与这三张桌子挂钩，我该怎么做？我的想法是 1：设置引用表current_order中的复合主键（paper_id，subscriber_id）的复合外键（paper_id，subscriber_id）。 2：分别在表current_order中设置两个单个外键（paper_id）和（subscriber_id）引用（paper_id）和）subscriber_id。

两种方法都不起作用，并且出现了错误1452：无法添加或更新子行。所以我真的很想知道在表收据和表current_order之间设置关系的正确方法是什么？这是E-R Digram：

E-R DIGRAM

表收据和表current_order之间有两个链接，我需要根据它设置关系。

Answer 1

我不是mysql专家，但我会尝试这个：

CREATE TABLE receipt (
id INTEGER PRIMARY KEY AUTO_INCREMENT,
receipt_date DATE,
paid_till_date DATE,
paper_id VARCHAR(20),
subscriber_id VARCHAR(10),
FOREIGN KEY (paper_id,subscriber_id) REFERENCES current_order (paper_id,subscriber_id)
   ON UPDATE CASCADE ON DELETE RESTRICT)
ENGINE = INNODB;

有用吗？

复合外键添加失败

1 个答案: