Add support for preserving field order?

Describe the use case

As far as I can tell, there doesn't seem to be a way to specify field order when adding a new column? Ive got an inherited model where it would be nice if any new fields that I create via an autogenerated revision would be entered into the database before the base classes fields.

I know I could manually add an execute after adding it to alter the table to insert it after another field but that sounds tedious to enforce and a way to preserve field order would be useful.

Databases / Backends / Drivers targeted

mysql in this example

Example Use

from sqlalchemy.orm import DeclarativeBase
from sqlalchemy.sql import func
from sqlalchemy.dialects.mysql import TIMESTAMP

class MyModel(MyBase):
   existing_field = ...
   new_field = ...

class MyBase(DeclarativeBase):
    created = Column(TIMESTAMP(fsp=2), server_default=func.now(), nullable=False)
    modified = Column(TIMESTAMP(fsp=2), onupdate=func.now(), nullable=False)

The new_field will be created at the end of the table

existing_field|created               |modified              |new_field|
-----------+----------------------+----------------------+------------+
          0|2017-02-08 16:38:14.65|2017-02-08 16:38:14.65|            |

where I'd like to have a way to insert it before a field

existing_field|new_field|created               |modified              |
-----------+------------+----------------------+----------------------+
          0|            |2017-02-08 16:38:14.65|2017-02-08 16:38:14.65|

Have a nice day!

Start by tracing how autogenerated revisions add new columns and how the MySQL backend handles column order. Compare the requested inherited-model ordering with the current behavior; done means a supported way to place a new field before an existing field while preserving current behavior for other databases.