I want to do an inner join across two tables so I can sort the rows in the first by a name value in the second.

The cat/mate example in the documentation isn't much help, because the join is to the same table. The various forum postings I've read aren't much help because the joins there always seem to involve joining via a bound parameter value.

In my own code "INNER JOIN" has no effect, presumably because the two properties/columns involved in the join have different names. If I do the join in the query myself with a "WHERE a.foo = b.bar" it works OK.

So I guess my questions are: a) is this true and b) if it is, is there ever a benefit to the JOIN keywords in HQL, other than as a shorthand?

HQL's join is not like an SQL join, because it uses an implicit join condition. If you need an explicit join condition, you have to use a theta join (where foo.bar = baz.bar).

Perhaps I wasn't clear; my query works with just the WHERE clause, and doesn't need the JOIN keyword in there.

This suggests that JOIN simply acts as a shortcut for the case where the properties being joined have the same name, and other than that has no purpose.

You can write your query in both styles in SQL. But if you have no association between the classes that are "joined" in HQL, you have to use a theta style "join".

HQL joins are not SLQ joins and yes, if you like, you can see them just as a shortcut "if the parameters have the same name", which is not the whole truth, but sufficent until you are more familiar with HQL. Don't think in tables and columns, think in classes, properties and associations.

OK, I see. In my case I just needed to join in order to sort the objects from the left side of the join, so that hadn't occurred to me.

Thanks Christian.