Question

CREATE TABLE IF NOT EXISTS `questions` (
  `question_id` int(11) NOT NULL AUTO_INCREMENT,
  `createddate` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `updateddate` timestamp NULL DEFAULT NULL,
  `active_flag` tinyint(4) NOT NULL DEFAULT '0',
  PRIMARY KEY (`question_id`),
  UNIQUE KEY `id_UNIQUE` (`question_id`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 AUTO_INCREMENT=1 ;

CREATE TABLE `alarts` (
  `alart_id` BIGINT(20) unsigned NOT NULL AUTO_INCREMENT,
  `alart_name` varchar(45) NOT NULL,
  `interval` int(10) unsigned NOT NULL,
  `alart_sent_counter` int(10) unsigned NOT NULL,
  `alart_types_id` BIGINT(20) unsigned NOT NULL,
  `contact_group_id` int(10) unsigned NOT NULL,
  PRIMARY KEY (`alart_id`),
  FOREIGN KEY (`alart_types_id`) REFERENCES alart_types(`alart_types_id`)
) ENGINE=InnoDB AUTO_INCREMENT=20 DEFAULT CHARSET=utf8;

I want to create new table with two FOREIGN KEY like this:

CREATE TABLE `alart_question_mapping` (
`alart_question_mapping_id` BIGINT(20) unsigned NOT NULL AUTO_INCREMENT,  
`question_id` int(11) NOT NULL,
`alart_id` BIGINT(20) unsigned NOT NULL,
PRIMARY KEY (`alart_question_mapping_id`),
FOREIGN KEY (`question_id`) REFERENCES questions(`question_id`),
FOREIGN KEY (`alart_id`) REFERENCES alart_types(`alart_id`)
) ENGINE=InnoDB AUTO_INCREMENT=20 DEFAULT CHARSET=utf8;

but I am getting error:
Error Code: 1005. Can’t create table ‘alart_question_mapping’ (errno: 150)

How can I create this table ?

Thank’s.

Answer 1

It can’t find table alart_types.

From MySQL Foreign Key Constraints

If you re-create a table that was dropped, it must have a definition
that conforms to the foreign key constraints referencing it. It must
have the right column names and types, and it must have indexes on the
referenced keys, as stated earlier. If these are not satisfied, MySQL
returns error number 1005 and refers to error 150 in the error
message.

I think you mean

FOREIGN KEY (`alart_id`) REFERENCES alart(`alart_id`)

instead of

FOREIGN KEY (`alart_id`) REFERENCES alart_types(`alart_id`)

Hope this makes sense.