1 files changed, 28 insertions, 2 deletions
diff --git a/lib/arel/algebra/relations/operations/join.rb b/lib/arel/algebra/relations/operations/join.rb
index 5d19873f62..83ebfc129f 100644
--- a/lib/arel/algebra/relations/operations/join.rb
+++ b/lib/arel/algebra/relations/operations/join.rb
@@ -44,6 +44,22 @@ module Arel
       relation1.engine != relation2.engine ? Memory::Engine.new : relation1.engine
     end
 
+    def table_sql(formatter = Sql::TableReference.new(self))
+      relation1.externalize.table_sql(formatter)
+    end
+
+    def joins(environment, formatter = Sql::TableReference.new(environment))
+      @joins ||= begin
+        this_join = [
+          join_sql,
+          relation2.externalize.table_sql(formatter),
+          ("ON" unless predicates.blank?),
+          (ons + relation2.externalize.wheres).collect { |p| p.bind(environment.relation).to_sql(Sql::WhereClause.new(environment)) }.join(' AND ')
+        ].compact.join(" ")
+        [relation1.joins(environment), this_join, relation2.joins(environment)].compact.join(" ")
+      end
+    end
+
     def == other
       super || Join === other &&
         relation1  == other.relation1 &&
@@ -68,9 +84,19 @@ module Arel
     end
   end
 
-  class InnerJoin  < Join; end
-  class OuterJoin  < Join; end
+  class InnerJoin < Join
+    def join_sql; "INNER JOIN" end
+  end
+
+  class OuterJoin < Join
+    def join_sql; "LEFT OUTER JOIN" end
+  end
+
   class StringJoin < Join
+    def joins(environment, formatter = Sql::TableReference.new(environment))
+       [relation1.joins(environment), relation2].compact.join(" ")
+    end
+
     def externalizable?
       relation1.externalizable?
     end