当进行:

DELETE FROM `jobs` WHERE `job_id` =1 LIMIT 1 

错误:

#1451 - Cannot delete or update a parent row: a foreign key constraint fails 
(paymesomething.advertisers, CONSTRAINT advertisers_ibfk_1 FOREIGN KEY 
(advertiser_id) REFERENCES jobs (advertiser_id))

这是我的表格:

CREATE TABLE IF NOT EXISTS `advertisers` (
  `advertiser_id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(255) NOT NULL,
  `password` char(32) NOT NULL,
  `email` varchar(128) NOT NULL,
  `address` varchar(255) NOT NULL,
  `phone` varchar(255) NOT NULL,
  `fax` varchar(255) NOT NULL,
  `session_token` char(30) NOT NULL,
  PRIMARY KEY (`advertiser_id`),
  UNIQUE KEY `email` (`email`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 AUTO_INCREMENT=2 ;


INSERT INTO `advertisers` (`advertiser_id`, `name`, `password`, `email`, `address`, `phone`, `fax`, `session_token`) VALUES
(1, 'TEST COMPANY', '', '', '', '', '', '');

CREATE TABLE IF NOT EXISTS `jobs` (
  `job_id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `advertiser_id` int(11) unsigned NOT NULL,
  `name` varchar(255) NOT NULL,
  `shortdesc` varchar(255) NOT NULL,
  `longdesc` text NOT NULL,
  `address` varchar(255) NOT NULL,
  `time_added` int(11) NOT NULL,
  `active` tinyint(1) NOT NULL,
  `moderated` tinyint(1) NOT NULL,
  PRIMARY KEY (`job_id`),
  KEY `advertiser_id` (`advertiser_id`,`active`,`moderated`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 AUTO_INCREMENT=2 ;


INSERT INTO `jobs` (`job_id`, `advertiser_id`, `name`, `shortdesc`, `longdesc`, `address`, `active`, `moderated`) VALUES
(1, 1, 'TEST', 'TESTTEST', 'TESTTESTES', '', 0, 0);

ALTER TABLE `advertisers`
  ADD CONSTRAINT `advertisers_ibfk_1` FOREIGN KEY (`advertiser_id`) REFERENCES `jobs` (`advertiser_id`);

当前回答

我在幼虫迁徙中也遇到过这个问题 在down()方法中,下拉表的顺序很重要

Schema::dropIfExists('groups');
Schema::dropIfExists('contact');

也许不行,但如果你改变顺序,就行了。

Schema::dropIfExists('contact');
Schema::dropIfExists('groups');

其他回答

如果您需要尽快支持客户端,又没有权限访问

FOREIGN_KEY_CHECKS

因此,数据完整性可以被禁用:

1)删除外键

ALTER TABLE `advertisers` 
DROP FOREIGN KEY `advertisers_ibfk_1`;

2)通过SQL或API激活您的删除操作

3)将外键添加回schema

ALTER TABLE `advertisers`
  ADD CONSTRAINT `advertisers_ibfk_1` FOREIGN KEY (`advertiser_id`) REFERENCES `jobs` (`advertiser_id`);

然而,这是一个热修复,因此风险由您自己承担,因为这种方法的主要缺陷是事后需要手动保持数据完整性。

同样,必须先删除广告主表中的行,然后才能删除它引用的作业表中的行。这样的:

ALTER TABLE `advertisers`
  ADD CONSTRAINT `advertisers_ibfk_1` FOREIGN KEY (`advertiser_id`) 
      REFERENCES `jobs` (`advertiser_id`);

...实际上与它应有的样子是相反的。事实上,这意味着你必须在广告客户之前在工作表中有一个记录。所以你需要使用:

ALTER TABLE `jobs`
  ADD CONSTRAINT `advertisers_ibfk_1` FOREIGN KEY (`advertiser_id`) 
      REFERENCES `advertisers` (`advertiser_id`);

一旦纠正了外键关系,delete语句就可以工作了。

如果要删除表,应在一个步骤中执行以下查询

设置FOREIGN_KEY_CHECKS = 0; DROP TABLE table_name;

创建数据库或表时

您应该在创建数据库或表的顶部脚本中添加这一行

SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=1;

现在要从表中删除记录?然后写成

SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=1;
DELETE FROM `jobs` WHERE `job_id` =1 LIMIT 1

好运!

如果有多个工作具有相同的advertiser_id,那么你的外键应该是:

ALTER TABLE `jobs`
ADD CONSTRAINT `advertisers_ibfk_1` 
FOREIGN KEY (`advertiser_id`) 
REFERENCES `advertisers` (`advertiser_id`);

否则(如果在你的情况下是相反的),如果你想在删除job中的行时自动删除advertiser中的行,则在外键的末尾添加'ON DELETE CASCADE'选项:

ALTER TABLE `advertisers`
ADD CONSTRAINT `advertisers_ibfk_1` 
FOREIGN KEY (`advertiser_id`) 
REFERENCES `jobs` (`advertiser_id`)
ON DELETE CASCADE;

检查外键约束