I have a wierd case. Suddenly some records (so many records) in one of the table are missing.. first, I tought it is caused by bug in my PHP script. But, I checked it, there's no DELETE operation in my script, only UPDATE. Does anyone knows what happen with my MySql?
Maybe you or someone who have access, restored database from dump?
I too think Some one might have executed SQL Injection by deleting rows or dropping tables
See here: http://owasp.com/index.php/SQL_Injection
Some stuff to check: If you use something like phpMyAdmin, make sure nobody can access it from outside.
If you use stored procedures verify them as well, some might delete. External applications might delete stuff from your database so strictly control who has privileges.
Also you can make sure you log all your operations and you can keep backups using the mysqldump command that you can compare daily: http://dev.mysql.com/doc/refman/5.1/en/mysqldump.html
Mihai