7 files changed, 12 insertions, 18 deletions
diff --git a/lib/arel/algebra/predicates.rb b/lib/arel/algebra/predicates.rb
index 5e17cdd101..d789c1d8a2 100644
--- a/lib/arel/algebra/predicates.rb
+++ b/lib/arel/algebra/predicates.rb
@@ -145,7 +145,13 @@ module Arel
       end
     end
 
-    class Inequality  < Equality
+    class Inequality  < Binary
+      def ==(other)
+        Equality === other and
+          ((operand1 == other.operand1 and operand2 == other.operand2) or
+           (operand1 == other.operand2 and operand2 == other.operand1))
+      end
+      
       def complement
         Equality.new(operand1, operand2)
       end
diff --git a/lib/arel/engines/memory/predicates.rb b/lib/arel/engines/memory/predicates.rb
index 0e88810e7d..8b3e5843cc 100644
--- a/lib/arel/engines/memory/predicates.rb
+++ b/lib/arel/engines/memory/predicates.rb
@@ -52,7 +52,7 @@ module Arel
       def operator; :== end
     end
 
-    class Inequality < Equality
+    class Inequality < Binary
       def eval(row)
         operand1.eval(row) != operand2.eval(row)
       end
diff --git a/lib/arel/engines/sql/core_extensions/nil_class.rb b/lib/arel/engines/sql/core_extensions/nil_class.rb
index d4bb0e4c33..ab990d6211 100644
--- a/lib/arel/engines/sql/core_extensions/nil_class.rb
+++ b/lib/arel/engines/sql/core_extensions/nil_class.rb
@@ -9,10 +9,6 @@ module Arel
         'IS NOT'
       end
 
-      def not_predicate_sql
-        'IS NOT'
-      end
-
       NilClass.send(:include, self)
     end
   end
diff --git a/lib/arel/engines/sql/core_extensions/object.rb b/lib/arel/engines/sql/core_extensions/object.rb
index 5415c84706..01c3c5479d 100644
--- a/lib/arel/engines/sql/core_extensions/object.rb
+++ b/lib/arel/engines/sql/core_extensions/object.rb
@@ -13,10 +13,6 @@ module Arel
         '!='
       end
 
-      def not_predicate_sql
-        '!='
-      end
-
       Object.send(:include, self)
     end
   end
diff --git a/lib/arel/engines/sql/predicates.rb b/lib/arel/engines/sql/predicates.rb
index df8700a500..59b0ab0929 100644
--- a/lib/arel/engines/sql/predicates.rb
+++ b/lib/arel/engines/sql/predicates.rb
@@ -52,7 +52,7 @@ module Arel
       end
     end
 
-    class Inequality < Equality
+    class Inequality < Binary
       def predicate_sql
         operand2.inequality_predicate_sql
       end
diff --git a/lib/arel/engines/sql/primitives.rb b/lib/arel/engines/sql/primitives.rb
index 41769fa510..15a27b2256 100644
--- a/lib/arel/engines/sql/primitives.rb
+++ b/lib/arel/engines/sql/primitives.rb
@@ -42,10 +42,6 @@ module Arel
       value.inequality_predicate_sql
     end
 
-    def not_predicate_sql
-      value.not_predicate_sql
-    end
-
     def to_sql(formatter = Sql::WhereCondition.new(relation))
       formatter.value value
     end
diff --git a/spec/engines/sql/unit/predicates/not_spec.rb b/spec/engines/sql/unit/predicates/noteq_spec.rb
index b124d4c80b..ed24627323 100644
--- a/spec/engines/sql/unit/predicates/not_spec.rb
+++ b/spec/engines/sql/unit/predicates/noteq_spec.rb
@@ -13,7 +13,7 @@ module Arel
       describe '#to_sql' do
         describe 'when relating to a non-nil value' do
           it "manufactures a not predicate" do
-            sql = Not.new(@attribute1, @attribute2).to_sql
+            sql = Inequality.new(@attribute1, @attribute2).to_sql
 
             adapter_is :mysql do
               sql.should be_like(%Q{`users`.`id` != `photos`.`user_id`})
@@ -35,7 +35,7 @@ module Arel
           end
 
           it "manufactures an is null predicate" do
-            sql = Not.new(@attribute1, @nil).to_sql
+            sql = Inequality.new(@attribute1, @nil).to_sql
 
             adapter_is :mysql do
               sql.should be_like(%Q{`users`.`id` IS NOT NULL})
@@ -54,7 +54,7 @@ module Arel
         describe "when relating to a nil Value" do
           it "manufactures an IS NULL predicate" do
             value = nil.bind(@relation1)
-            sql = Not.new(@attribute1, value).to_sql
+            sql = Inequality.new(@attribute1, value).to_sql
 
             adapter_is :mysql do
               sql.should be_like(%Q{`users`.`id` IS NOT NULL})