Question

创建外键时我遇到了这个奇怪的问题。

给出2个表：

CREATE TABLE IF NOT EXISTS `groupdeals` (
  `groupdeals_id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `product_id` int(10) NOT NULL,
  `merchant_id` int(11) NOT NULL,
  `minimum_qty` int(11) NOT NULL,
  `maximum_qty` int(11) NOT NULL,
  `target_met_email` int(11) NOT NULL,
  `coupon_barcode` text NOT NULL,
  `coupon_merchant_address` int(11) NOT NULL,
  `coupon_merchant_contact` int(11) NOT NULL,
  `coupon_expiration_date` date DEFAULT NULL,
  `coupon_price` int(11) NOT NULL,
  `coupon_fine_print` int(11) NOT NULL,
  `coupon_highlights` int(11) NOT NULL,
  `coupon_merchant_description` int(11) NOT NULL,
  `coupon_business_hours` int(11) NOT NULL,
  `coupon_merchant_logo` int(11) NOT NULL,
  `coupon_additional_info` text NOT NULL,
  `position` int(11) NOT NULL,
  PRIMARY KEY (`groupdeals_id`),  
  KEY `groupdeals_id` (`groupdeals_id`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8;

和

CREATE TABLE IF NOT EXISTS `groupdeals_coupons` (
  `coupon_id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `groupdeals_id` int(11) NOT NULL,
  `order_item_id` int(11) NOT NULL,
  `coupon_code` varchar(255) NOT NULL DEFAULT '',
  `redeem` varchar(255) NOT NULL DEFAULT '',
  `status` varchar(255) NOT NULL DEFAULT '',
  PRIMARY KEY (`coupon_id`),
  KEY `fk_groupdeals_coupons_groupdeals1_idx` (`groupdeals_id`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8;

我尝试通过执行以下查询来添加外键：

ALTER TABLE `groupdeals_coupons` 
ADD CONSTRAINT `fk_groupdeals_coupons_groupdeals1`
  FOREIGN KEY (`groupdeals_id`)
  REFERENCES `groupdeals` (`groupdeals_id`)
  ON DELETE CASCADE
  ON UPDATE CASCADE;

我收到的只是错误：

#1215 - Cannot add foreign key constraint

显示引擎innodb状态

------------------------
LATEST FOREIGN KEY ERROR
------------------------
2013-08-17 13:47:49 7ff5dbb2c700 Error in foreign key constraint of table xxxxx/#sql-7b23_282b1a:

 FOREIGN KEY (`groupdeals_id`)
 REFERENCES `groupdeals` (`groupdeals_id`)
 ON DELETE CASCADE
 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.
Note that the internal storage type of ENUM and SET changed in
tables created with >= InnoDB-4.1.12, and such columns in old tables
cannot be referenced by such columns in new tables.
See http://dev.mysql.com/doc/refman/5.6/en/innodb-foreign-key-constraints.html
for correct foreign key definition.

列groupdeals.groupdeals_id是主要的，所以我真的无法理解问题出在哪里：|

任何提示？

服务器类型：Percona Server 服务器版本：5.6.11-rc60.3-log - Percona Server（GPL），版本60.3

Answer 1

您的类型不一致：

CREATE TABLE IF NOT EXISTS `groupdeals` (
  `groupdeals_id` int(11) unsigned NOT NULL AUTO_INCREMENT,

CREATE TABLE IF NOT EXISTS `groupdeals_coupons` (
  [...]
  `groupdeals_id` int(11) NOT NULL,

正如您将看到的，在一个表中您有int unsigned。另一方面，只有int。

顺便说一句，我注意到groupdeals_id上有两个键。这是故意的吗？

CREATE TABLE IF NOT EXISTS `groupdeals` (
  [...]
  PRIMARY KEY (`groupdeals_id`),  
  KEY `groupdeals_id` (`groupdeals_id`)

Answer 2

尝试以下两个步骤添加外键： -

alter table groupdeals_coupons modify groupdeals_id int unsigned not null default 0;
ALTER TABLE groupdeals_coupons ADD CONSTRAINT fk_groupdeals_coupons_groupdeals1 FOREIGN KEY (groupdeals_id) references groupdeals (roupdeals_id);

＃1215 - 无法添加外键约束

2 个答案: