Abstracted JOIN for maintainability?

Does anyone know an ORM that can abstract JOINs? I'm using PHP, but I would take idea开发者_如何学Cs from anywhere. I've used Doctrine ORM, but I'm not sure if it supports this concept.

I would like to be able to specify a relation that is actually a complicated query, and then use that relation in other queries. Mostly this is for maintainability, so I don't have a lot of replicated code that has to change if my schema change. Is this even possible in theory (at least for some subset of "complicated query")?

Here's an example of what I'm talking about:

ORM.defineRelationship('Message->Unresponded', '
  LEFT JOIN Message_Response
    ON Message.id = Message_Response.Message_id
  LEFT JOIN Message AS Response
    ON Message_Response.Response_id = Response.id
  WHERE Response.id IS NULL
');

ORM.query('
  SELECT * FROM Message
  SUPER_JOIN Unresponded
');

Sorry for the purely invented syntax. I don't know if anything like this exists. It would certainly be complicated if it did.

One possibility would be to write this join as a view in the database. Then you can use any query tools on the view.

Microsofts Entity Framework also supports very complex mappings between code entities and the database tables, even crossing databases. The query you've given as an example would be easily supported in terms of mapping from that join of tables to an entity. You can then execute further queries against the resulting joined data using LINQ. Of course if you're using PHP this may not be a huge amount of use to you.

However I'm not aware of a product that wraps up the join into the syntax of further queries in the way you've shown.