[Django]-Django & South: Adding new field but DatabaseError occurs "table already exists"

You need to do schemamigration app --initial first without your new field, then migrate app --fake 0001 (or whichever migration number it returned) to set the south database to that state (tables already created).

Add your new field, then run schemamigration myapp --auto, then migrate.

I commented out the field, ran schemamigration, then migrate. Uncommented out the field, ran schemamigration, then migrate and it worked. Not sure what I was doing wrong.

This happens when you doing something on migration and did not let south knows about it.

If you looking at the south_* table in the database, you will find-out south keeps logs about db migrations in the database. The common way is to faking the migration.
There is a fake argument for the South.

here you can find out what is all about:
http://south.readthedocs.org/en/latest/commands.html#options