I'm not sure I understand the question. I've used an ORM with a codebase that used different databases in development and production, so in that sense, yes. But

I'm not sure I understand the question. I've used an ORM with a codebase that used different databases in development and production, so in that sense, yes. But if you mean "swapping" a production database for another, that's not really how I'd describe it. If you're switching from one database system to another, that sounds like a major migration, not just a "swap." You can't exactly just drop a SQL Server database into PostgreSQL and assume all is well, can you? So I'm not sure where the ORM angle comes into this — a major database migration is a task in itself. (Or maybe I'm just a bad sysadmin? Entirely possible, I suppose.)