Cannot delete MySQL trigger. Appears in information_schema, but no .TRN file

Question

I have a MySQL database with a few tables and triggers. A process was trying to drop one of the triggers and it failed with the following error:

Malformed file type header in file 'trigger_name.TRN'

I tried to drop the trigger manually, but obviously got the same error. So I went ahead and deleted the .TRN file itself (was that a bad idea?).

After deleting the .TRN file, the trigger still appears in information_schema.TRIGGERS. If I try to drop it I get error "Trigger does not exist". If I try to create another trigger with the same name, table and event manipulation I get error "Trigger already exists".

I don't know what else to do. How can I really delete this trigger so that it can be created again?

MySQL version is 5.0.22 and all tables are MyISAM.

SHOW CREATE TABLE outputs:

CREATE TABLE `cash_operation` (
  `id` int(11) NOT NULL auto_increment,
  `amount` decimal(16,8) NOT NULL default '0.00000000',
  `comment` varchar(500) NOT NULL default '',
  `reason_id` int(11) NOT NULL default '-1',
  `date` datetime NOT NULL default '1980-01-01 00:00:00',
  `reconciliation_number` int(11) NOT NULL default '-1',
  `reason_desc` varchar(250) NOT NULL default '',
  `automatic` tinyint(1) NOT NULL default '0',
  `employee_id` int(11) NOT NULL default '-1',
  `employee_code` varchar(250) NOT NULL default '',
  `employee_name` varchar(250) NOT NULL default '',
  `payed_employee_id` int(11) NOT NULL default '-1',
  PRIMARY KEY  (`id`),
  KEY `cash_operation_reason_id` USING BTREE (`reason_id`),
  KEY `cash_operation_reconciliation_number` USING BTREE (`reconciliation_number`),
  KEY `cash_operation_automatic` USING BTREE (`automatic`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8

SELECT @@global.datadir; results in error "Unkown system variable 'datadir'"

Answer 1

Based on the suggestion I gave in the chat room, here is my answer

1. CREATE TABLE cash_op LIKE cash_operation;
2. Goto the datadir in your Windows server
3. rename cash_op.MYD cash_op.MYX
4. copy cash_operation.MYD cash_op.MYD
5. login to mysql and run
   • REPAIR TABLE cash_op;
   • ALTER TABLE cash_operation RENAME cash_op_old;
   • ALTER TABLE cash_op RENAME cash_operation;
6. Go create the two triggers on the new cash_operation table

You said in the chat room : Awesome, that worked! You can post it as the answer.

I am glad you gave it a try and it worked for you !!!

BTW you can drop the old table with DROP TABLE cash_op_old;