Question

似乎添加包含外键的复合唯一键会破坏表：无法删除唯一键：

drop index test_unq on order_test

错误：

Cannot drop index 'test_unq': needed in a foreign key constraint

重现的步骤：

create table product_test (
    id bigint unsigned not null auto_increment primary key
);

create table order_test (
    id bigint unsigned not null auto_increment primary key,
    product_id bigint unsigned not null,
    foreign key (product_id) references product_test(id)
);

alter table order_test add some_field int not null;

alter table order_test add unique test_unq(product_id, some_field);

正在运行

SHOW CREATE TABLE order_test

返回

CREATE TABLE `order_test` (
  `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
  `product_id` bigint(20) unsigned NOT NULL,
  `some_field` int(11) NOT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `test_unq` (`product_id`,`some_field`),
  CONSTRAINT `order_test_ibfk_1` FOREIGN KEY (`product_id`) REFERENCES 
        `product_test` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci

结果看起来无效，有一个约束但没有product_id的键。

有关如何恢复表而不删除并再次创建它的任何想法？

谢谢！

编辑：

删除所有其他外键无济于事！删除后的结构：

CREATE TABLE `order_test` (
  `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
  `product_id` bigint(20) unsigned NOT NULL,
  `some_field` int(11) NOT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `test_unq` (`product_id`,`some_field`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci

当我尝试删除索引时出现相同的错误。

drop index test_unq on order_test

错误：

Cannot drop index 'test_unq': needed in a foreign key constraint

MySQL复合唯一键和外键错误

0 个答案: