MySQL data directory deleted

InnoDB tables cannot be copied the same way that MyISAM tables can.

Just copying the .frm and .ibd files from one location to another is asking for trouble. Copying the .frm and .ibd file of an InnoDB table is only good if and only if you can guarantee that the tablespace id of the .ibd file matches exactly with the tablespace id entry in the metdata of the ibdata1 file.

I wrote two posts in DBA StackExchange about this tablespace id concept

• Table compression in InnoDB? (under the heading 'Restoring Databases')
• How to Recover an InnoDB table whose files were moved around

Here is excellent link on how to reattach any .ibd file to ibdata1 in the event of mismatched tablespace ids : http://www.chriscalender.com/?tag=innodb-error-tablespace-id-in-file. After reading this, you should come to the immediate realization that copying .ibd files is just plain crazy.

You could apply the suggestions from the Chris Calendar link, or you could go back to the old installation of mysql, startup up mysql, and then mysqldump the ddms database. Then, import that mysqldump into your new mysql instance. Trust me, this would be far easier.

The MainDB.res is not the Actual database.Someone by mistake have created it in your data directory.

Have a look at the content of my datadir

-rwx------ 1 mysql mysql     0 2012-05-23 14:48 debian-5.1.flag
drwx------ 2 mysql mysql  4096 2012-05-28 16:09 mysql
-rwx------ 1 mysql mysql     6 2012-05-23 14:49 mysql_upgrade_info
-rw-rw---- 1 mysql mysql     5 2012-05-29 09:15 OSS-240.pid
drwx------ 2 mysql mysql 36864 2012-05-28 16:58 test
drwx------ 2 mysql mysql  4096 2012-05-29 10:39 world
drwxr-xr-x 2 mysql mysql   4096 2012-05-29 14:29 world.res

where world.res is the directory which i have created as

mkdir world.res

and now when i want to acess it in the MySQL Shell see the result(The world.res is created as #mysql50#world.res by itself. )

mysql> use #mysql50#world.res
ERROR 1102 (42000): Incorrect database name '#mysql50#world.res'

So in my opinion the MainDB.res is not the database.

UPDATE

In MySQL you can't create the Database's that contains the word "."

mysql> create database test.res;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '.res' at line 1

so it is sure that that was not your database.