Rails 3活动记录问题

我有几个问题要问你Rails 3专家那里。你怎么能做到以下几点?

@items = (@itemsA + @itemsB).order("name ASC")

@item = Item.where("type = ?" and "condition = ?", "book", "new")

@commenteditems = Item.find_all_by_type_and_condition("book", "new").include("notes").select("item[name]", "notes[note]")

@selecteditems = @items.where("select = ?", true)