The 'Copy table to different db/host' facility allows the target table/db to be the same as source table/db. So, if you forget to select the proper target table/db this could default to the same as your source table/db. If you have also selected the 'Drop table if exists in target', the result is devastating, as the data in the source table gets dropped. SQLyog should include better vaildation to prevent this from happening in error. I lost 30,000 rows in a production table – fortunately I had backed this up the previous day.