/* ForeignKey CHANGE */
ALTER TABLE CHANGE //修改表结构,表名:CHANGE
ADD CONSTRAINT CHANGE //添加约束,约束名:CHANGE --注:同名不好
FOREIGN KEY (CHANGE) // 外键关系,外键字段:CHANGE --注:同名不好
REFERENCES CHANGE_CODE; //主表名:CHANGE_CODE,这是简便写法,取CHANGE_CODE的主键,最好写成REFERENCES CHANGE_CODE(CHANGE)/* ForeignKey STUDENT1 */
ALTER TABLE CHANGE //这个和前一个一样,不多写了
ADD CONSTRAINT STUDENT1
FOREIGN KEY (STUDENT)
REFERENCES STUDENT;
ALTER TABLE CHANGE //修改表结构,表名:CHANGE
ADD CONSTRAINT CHANGE //添加约束,约束名:CHANGE --注:同名不好
FOREIGN KEY (CHANGE) // 外键关系,外键字段:CHANGE --注:同名不好
REFERENCES CHANGE_CODE; //主表名:CHANGE_CODE,这是简便写法,取CHANGE_CODE的主键,最好写成REFERENCES CHANGE_CODE(CHANGE)/* ForeignKey STUDENT1 */
ALTER TABLE CHANGE //这个和前一个一样,不多写了
ADD CONSTRAINT STUDENT1
FOREIGN KEY (STUDENT)
REFERENCES STUDENT;
--修改表change
ADD CONSTRAINT CHANGE
---给列名为change的外键约束
FOREIGN KEY (CHANGE)
REFERENCES CHANGE_CODE;
----外键与 change_code的change列
/* ForeignKey STUDENT1 */
ALTER TABLE CHANGE
--修改表change
ADD CONSTRAINT STUDENT1
---给列名为STUDENT1的加上外键约束
FOREIGN KEY (STUDENT)
REFERENCES STUDENT;
----外键与 change_code表的change列