Question

I have two tables named

MEMBER – columns id(primary key), name, email &

TOPICS – columns id, topic_type, created_by.

I want to create a new table MEMBER_TO_TOPICS which maps member to topics, which has columns memberid(foreign key of member table id), topicid(foreign key of topic table id), created_time.
Here is the query am trying to execute .

CREATE TABLE `gsraisin`.`member_to_topics` (
`member_id` VARCHAR(50) NOT NULL,
`topic_id` VARCHAR(50) NOT NULL,
`created_date` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
PRIMARY KEY (`member_id`, `topic_id`),
CONSTRAINT `FK_member_to_topics_memberid` FOREIGN KEY `FK_member_to_topics_memberid`   
(`member_id`)
REFERENCES `member` (`id`)
ON DELETE CASCADE
ON UPDATE NO ACTION,
CONSTRAINT `FK_member_to_topics_topicid` FOREIGN KEY `FK_member_to_topics_topicid` 
(`topic_id`)
REFERENCES `topics` (`id`)
ON DELETE CASCADE
ON UPDATE NO ACTION
)
ENGINE = InnoDB;

But getting the following error while executing – MYSQL Error Number 1005 can’t Create table member_to_topics (errno:121)

Answer 1

I tried this on my local machine and it worked fine.

mysql> show create table member;
+--------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table  | Create Table                                                                                                                                                                                       |
+--------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| member | CREATE TABLE `member` (
  `id` varchar(50) NOT NULL DEFAULT '',
  `name` varchar(50) DEFAULT NULL,
  `email` varchar(50) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+--------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)


mysql> show create table topics;
+--------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table  | Create Table                                                                                                                                                                                                  |
+--------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| topics | CREATE TABLE `topics` (
  `id` varchar(50) NOT NULL DEFAULT '',
  `topic_type` varchar(50) DEFAULT NULL,
  `created_by` varchar(50) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+--------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql> show create table member_to_topics;
+------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table            | Create Table                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
+------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| member_to_topics | CREATE TABLE `member_to_topics` (
  `member_id` varchar(50) NOT NULL,
  `topic_id` varchar(50) NOT NULL,
  `created_date` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`member_id`,`topic_id`),
  KEY `FK_member_to_topics_topicid` (`topic_id`),
  CONSTRAINT `FK_member_to_topics_memberid` FOREIGN KEY (`member_id`) REFERENCES `member` (`id`) ON DELETE CASCADE ON UPDATE NO ACTION,
  CONSTRAINT `FK_member_to_topics_topicid` FOREIGN KEY (`topic_id`) REFERENCES `topics` (`id`) ON DELETE CASCADE ON UPDATE NO ACTION
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

Error code 121 is for Duplicate Key.

[matthewh@kookaburra ~]$ perror 121
OS error code 121:  Remote I/O error
MySQL error code 121: Duplicate key on write or update

I suspect you may have a duplicated constraint name perhaps?