MySQL修改表的外键约束

创建表

CREATE TABLE parent(id INT NOT NULL, PRIMARY KEY(id))ENGINE=INNODB;
CREATE TABLE child(id INT,parent_id INT,FOREIGN KEY(parent_id) REFERENCES parent(id))ENGINE=INNODB;
 
insert into parent(id) values(1);
insert into child values(1,1);

select * from parent;
select * from child;

update parent set id = 2 where id = 1;

删除约束

首先查看约束名：

show create table child;

则child_ibfk_1是外键名称，删除外键

 ALTER TABLE child DROP FOREIGN KEY child_ibfk_1

增加约束

ALTER TABLE child ADD CONSTRAINT  FOREIGN KEY(parent_id) REFERENCES parent(id);

ALTER TABLE child ADD CONSTRAINT KF_PARENT_CHILD FOREIGN KEY(parent_id) REFERENCES parent(id);