错误 1215：无法添加外键约束（InnoDB）

Question

我正在努力使用以下查询创建外键：

alter table `users` add constraint `users_sales_partner_id_foreign` foreign key (`sales_partner_id`) references `structures` (`sales_partner_id`) on update cascade

InnoDB 日志说，它无法匹配这个索引：

2017-02-27 10:25:47 Error in foreign key constraint of table website_backend/users: foreign key (sales_partner_id) references structures (sales_partner_id) on update cascade: Cannot find an index in the referenced table where the referenced columns appear as the first columns, or column types in the table and the referenced table do not match for constraint.

我已经检查了拼写错误和数据类型不兼容，但似乎一切正常：

CREATE TABLE `users` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `profile_id` int(10) unsigned NOT NULL,
  `sales_partner_id` int(11) NOT NULL,
  `email` varchar(191) COLLATE utf8mb4_unicode_ci NOT NULL,
  `password` varchar(191) COLLATE utf8mb4_unicode_ci NOT NULL,
  `state` enum('pending','confirmed','active','deactivated') COLLATE utf8mb4_unicode_ci NOT NULL,
  `created_at` timestamp NULL DEFAULT NULL,
  `updated_at` timestamp NULL DEFAULT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `users_profile_id_unique` (`profile_id`),
  UNIQUE KEY `users_sales_partner_id_unique` (`sales_partner_id`),
  UNIQUE KEY `users_email_unique` (`email`),
  CONSTRAINT `users_profile_id_foreign` FOREIGN KEY (`profile_id`) REFERENCES `profiles` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci

CREATE TABLE `structures` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `sales_partner_id` int(11) NOT NULL,
  `sales_partner_structure` int(11) DEFAULT NULL,
  `active` tinyint(1) NOT NULL,
  `blocked` tinyint(1) NOT NULL,
  `created_at` timestamp NULL DEFAULT NULL,
  `updated_at` timestamp NULL DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci

我无法解决我的问题，有人知道吗？提前致谢！

Answer 1

感谢 Paul Spiegel 提醒我只能将 FK 设置到索引字段。经过另一次审查后，我发现我的引用字段未编入索引，这解决了我的问题。

错误 1215：无法添加外键约束（InnoDB）

Error 1215: Can't add foreign key constraint (InnoDB)

mysql

innodb

foreign-keys