无法放置放下键,即使它存在:错误代码:1091

时间:2019-01-09 18:01:37

标签: mysql foreign-keys

我有一个看起来像这样的表:

CREATE TABLE `articles` 
             ( 
                          `article_id` INT(10) NOT NULL auto_increment, 
                          `pubsrc_id`  INT(10) NOT NULL, 
                          `pub_id`     VARCHAR(16) NOT NULL
                          PRIMARY KEY (`article_id`), 
                          UNIQUE KEY `pubsrc_id` (`pubsrc_id`,`pub_id`), 
                          CONSTRAINT `pub_articles_ibfk_1` FOREIGN KEY (`pubsrc_id`) REFERENCES `pub_sources` (`pubsrc_id`) ON
             DELETE RESTRICT 
             ON 
             UPDATE RESTRICT, 
                    CONSTRAINT `pub_articles_ibfk_2` FOREIGN KEY (`pubsrc_id`) REFERENCES `pub_sources` (`pubsrc_id`)
             ) 

还有另一个表,上一个表有一个键:

         CREATE TABLE `pub_sources` 
         ( 
                      `pubsrc_id`              INT(11) NOT NULL, 
                      `pubsrc_name`            VARCHAR(32) NOT NULL
                      PRIMARY KEY (`pubsrc_id`) 
         ) 

我正在尝试使用以下命令删除foregin键:

SET SESSION SQL_SAFE_UPDATES = 0;
SET FOREIGN_KEY_CHECKS = 0;
ALTER TABLE `articles` DROP FOREIGN KEY `pubsrc_id`;

但出现以下错误:

Error Code: 1091. Can't DROP 'pubsrc_id'; check that column/key exists

1 个答案:

答案 0 :(得分:1)

您需要通过其约束名称而不是其定义列的名称来删除外键。

不行:

mysql> ALTER TABLE `articles` DROP FOREIGN KEY `pubsrc_id`;
ERROR 1091 (42000): Can't DROP 'pubsrc_id'; check that column/key exists

好的:

mysql> ALTER TABLE `articles` DROP FOREIGN KEY `pub_articles_ibfk_1`;
Query OK, 0 rows affected (0.03 sec)