4 files changed, 23 insertions, 7 deletions
diff --git a/lib/arel/engines/sql/core_extensions/nil_class.rb b/lib/arel/engines/sql/core_extensions/nil_class.rb
index 3f70677ba6..d4bb0e4c33 100644
--- a/lib/arel/engines/sql/core_extensions/nil_class.rb
+++ b/lib/arel/engines/sql/core_extensions/nil_class.rb
@@ -4,6 +4,10 @@ module Arel
       def equality_predicate_sql
         'IS'
       end
+      
+      def inequality_predicate_sql
+        'IS NOT'
+      end
 
       def not_predicate_sql
         'IS NOT'
diff --git a/lib/arel/engines/sql/core_extensions/object.rb b/lib/arel/engines/sql/core_extensions/object.rb
index b71ef29fd5..5415c84706 100644
--- a/lib/arel/engines/sql/core_extensions/object.rb
+++ b/lib/arel/engines/sql/core_extensions/object.rb
@@ -8,6 +8,10 @@ module Arel
       def equality_predicate_sql
         '='
       end
+      
+      def inequality_predicate_sql
+        '!='
+      end
 
       def not_predicate_sql
         '!='
diff --git a/lib/arel/engines/sql/predicates.rb b/lib/arel/engines/sql/predicates.rb
index b459168620..df8700a500 100644
--- a/lib/arel/engines/sql/predicates.rb
+++ b/lib/arel/engines/sql/predicates.rb
@@ -30,21 +30,19 @@ module Arel
       def predicate_sql; "AND" end
     end
     
-    class GroupedPredicate < Polyadic
+    class Polyadic < Predicate
       def to_sql(formatter = nil)
         "(" + 
-          additional_operands.inject([]) { |predicates, operand|
-            predicates << operator.new(operand1, operand).to_sql(formatter)
-          }.join(" #{predicate_sql} ") +
+          predicates.map {|p| p.to_sql(formatter)}.join(" #{predicate_sql} ") +
         ")"
       end
     end
     
-    class Any < GroupedPredicate
+    class Any < Polyadic
       def predicate_sql; "OR" end
     end
     
-    class All < GroupedPredicate
+    class All < Polyadic
       def predicate_sql; "AND" end
     end
 
@@ -55,7 +53,9 @@ module Arel
     end
 
     class Inequality < Equality
-      def predicate_sql; '!=' end
+      def predicate_sql
+        operand2.inequality_predicate_sql
+      end
     end
 
     class GreaterThanOrEqualTo < Binary
diff --git a/lib/arel/engines/sql/primitives.rb b/lib/arel/engines/sql/primitives.rb
index 78e1ed7f0b..41769fa510 100644
--- a/lib/arel/engines/sql/primitives.rb
+++ b/lib/arel/engines/sql/primitives.rb
@@ -29,10 +29,18 @@ module Arel
     def inclusion_predicate_sql
       value.inclusion_predicate_sql
     end
+    
+    def exclusion_predicate_sql
+      value.exclusion_predicate_sql
+    end
 
     def equality_predicate_sql
       value.equality_predicate_sql
     end
+    
+    def inequality_predicate_sql
+      value.inequality_predicate_sql
+    end
 
     def not_predicate_sql
       value.not_predicate_sql