Re: Considering future support for different databases.

[psini]

I'm not sure I understand your question: do you want a cross-db app or an app which can be optimized for each db system?

To make a cross-db app I would try and use only the most standard SQL queries, avoiding system or db-dependent syntax instead of adapting the queries to every SQL dialect.

[Cap'n Steve]

I guess I'd always assumed that a cross-db app would have to be optimized for each system unless the database was extremely simple. Does anyone know of any examples of a project that manages to be compatible with several different databases with no special considerations for any of them?

[Joost]

I'd guess that most systems that use a full-grown ORM library have all the db-specific code in the underlying (and reusable) ORM layer, and when they do use hand-written DB specific SQL, it's only to optimize a few "interesting" JOINs).

Note that most ORM layers do rely on some standardization of the database schema (especially concerning naming of tables and columns, and limiting the available column types), but that doesn't mean the schemas themselves are simple at all.