方法一:直接在属性值后面添加
create table score(
cscore int(11),
st_id int(50) references student(id),
cs_id int(30) references classes(id),
primary key(st_id,cs_id)
);
方法二:
create table score(
cscore int(11),
st_id int(50),
cs_id int(30),
primary key(st_id,cs_id),
FOREIGN KEY (st_id) REFERENCES student(id),
FOREIGN KEY (cs_id) REFERENCES classes(id)
);
方法三:添加约束
create table score(
cscore int(11),
st_id int(50),
cs_id int(30),
primary key(st_id,cs_id),
CONSTRAINT FK_ID_ST
FOREIGN KEY (st_id) REFERENCES student(id),
CONSTRAINT FK_ID_CS
FOREIGN KEY (cs_id) REFERENCES classes(id)·
);
方法四:在表的定义外进行添加
alter table 表名 add constraint FK_ID foreign key(你的外键字段名) REFERENCES 外表表名(对应的表的主键字段名);
参考:
https://www.cnblogs.com/qisong178878915/p/4435488.html
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