title: mySQL select differences between two tables in different databases
body: <p>I have two databases: old and new.<br>
  Both have a comments table. There are 100 comments in the old table that are not in the new. Comments have been added to the new table and there is a conflict in IDs so querying by ID will not be an option.  I need so isolate the 100 comments that that they can be exported and inserted into the new database.</p>
  
  <p>I know there are 100 because I have tried using some mysql data compare tools. Unfortunately all of those tools just want to update the comments in the new table with the old content.</p>
  
  <p>Is there a query I can run to get the 100 comments?</p>