How to use DSL to create a derived table join?

[wuarmin]

Hey,
I cannot find examples, which show how to join a derived table.

I.e. how to build following SQL with DSL:

select *
from table
left_join(
  select id, max(amount)
  from table2
  group by id
) as temp on table.id = table2.id
where table.test = true

where(test: true).left_join do
  # ???
end

thanks!
best regards

[jeremyevans]

DB[:table].
  left_join(DB[:table2].
      select_group(:id).
      select_append{max(:amount)},
    :id=>:id).
  where{{table[:test]=>true}}

[wuarmin]

Thanks!