Question

我有一张桌子

TABLE PARTECIPATION
(PARTY_ID INT,
GUEST ...
PRIMARY KEY(PARTY_ID, GUEST)
FOREIGN KEY(PARTY_ID) REFERENCES PARTY(ID)
FOREIGN KEY(GUEST) REFERENCES GUEST(GUEST)
)

还有一张客人桌

TABLE GUEST
(NAME VARCHAR(20),
SURNAME VARCHAR(20),
AGE INT,

PRIMARY KEY(NAME, SURNAME)
)

现在，我如何将PARTECIPATION的GUEST元素设置为GUEST TABLE的外键？

我应该在GUEST中创建一个名为idk，ID的列并将其设置为主键吗？或者我可以做这样的事情：

TABLE PARTECIPATION
(PARTY_ID INT,
GUEST_NAME VARCHAR(20),
GUEST_SURNAME VARCHAR(20)
PRIMARY KEY(PARTY_ID, GUEST_NAME, GUEST_SURNAME)
FOREIGN KEY(PARTY_ID) REFERENCES PARTY(ID),
FOREIGN KEY(GUEST_NAME) REFERENCES GUEST(NAME),
FOREIGN KEY(GUEST_SURNAME) REFERENCES GUEST(SURNAME))

Answer 1

外键必须具有与其引用的主键相同的列数和相同的顺序。这意味着，如果PK具有多个列，则必须将多个列放入一个外键定义中。

TABLE PARTECIPATION
(PARTY_ID INT,
GUEST_NAME VARCHAR(20),
GUEST_SURNAME VARCHAR(20)
PRIMARY KEY(PARTY_ID, GUEST_NAME, GUEST_SURNAME)
FOREIGN KEY(PARTY_ID) REFERENCES PARTY(ID),
FOREIGN KEY(GUEST_NAME, GUEST_SURNAME) REFERENCES GUEST(NAME, SURNAME))

复合主键作为外键MySQL

1 个答案: