mysema/querydsl — pull request #542 by msiedlarek (2013-11-05 06:19:07+00:00)
Title: Allow explicit SQL joins to expressions

Currently you can join expressions (such as `Path` interface) only through implicit join in a `FROM` clause. Many database engines (e.g. PostgreSQL) have trouble with mixing explicit and implicit joins so the user should always have a choice between them.

Example use case:

```
final PathBuilder path = new PathBuilder<>(Tuple.class, "some_alias");
query.withRecursive(
path,
field1,
field2
).as(
sq().unionAll(
someSubQuery,
sq().from(someTable).join(path).on(...).leftJoin(...).on(...)
)
)
```

Explicit join in a subquery is required for it to work correctly on Postgres.