I'm having issues adding a Foreign Key to link 2 existing tables together.  Table A has data, and I need it to reference Table B (which also has data).  
I will need to insert a row (or rows) into Table B which Table A will reference.  
In this case it is acceptable to insert a row into Table B and then use that as the default value for the migration. That would require that I know the ID of the row that I'm inserting.  
I think that I can handle everything except figuring out the ID of the row that I insert into Table B.  
Is it possible to return data inside of Migrations?
