Custom column names in fragment

Is there a way to use custom/varying column names in fragment? I mean the situation where I have 2 almost similar tables coming from different databases. Only couple of columns are different for historical reasons and I use those column names inside fragment(s). I want to unify Ecto queries to both of those tables as they were executed separately before.

Using simple questionmark notation fragment("?", column_name) causes column name to be appended into fragment however column ends up wrapped into double-quotes which is not desired.

Here is an example:

{:ok, datetime} = DateEx.convert_date_to_datetime(date)

CheapestConnection
|> where([cc], cc.kind == "round_trip_recent")
|> order_by([cc], fragment("abs(date_part('day', departure_date - ?)), price", type(^datetime, :utc_datetime)))    
|> CheapestConnectionsRepo.all()

The column I would like to choose depending on certain conditions (like DB/Repo is used) is departure_date. That column name is different in another database. As a side note this query basically orders records by closest date relative to datetime.