题解 | 建表后通过 ALTER TABLE 添加外键
在audit表上创建外键约束，其emp_no对应employees_test表的主键id
https://www.nowcoder.com/practice/aeaa116185f24f209ca4fa40e226de48
alter table audit add constraint fk_emp_no foreign key (EMP_no) references employees_test (ID) on delete restrict on update CASCADE -- 给已存在的employees表添加外键 # ALTER TABLE employees # ADD CONSTRAINT fk_emp_dept -- 外键名称 # FOREIGN KEY (dept_no) # REFERENCES departments (dept_no) # ON DELETE RESTRICT # ON UPDATE CASCADE;
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