New migration command: Copy

I would like to implement a new migration command. Other commands such as create, update, delete, etc are for modifying the schema. I would like to implement a suit of commands for modifying the data. Normally this is done with the data sync scripts, which is great for creating records that need to exist, however if we need to modify existing data there is nothing that can handle this automatically.

Use case here is moving data from one table to another. An existing table has a new column added which currently has data that exists in a different table. Once this new column is created we need to copy the data from the one table into the new table column, then we can remove the old table completely.