build expression not(nil) as IS NOT NULL

4 files changed, 15 insertions, 1 deletions

diff --git a/lib/arel/engines/sql/core_extensions/nil_class.rb b/lib/arel/engines/sql/core_extensions/nil_class.rb
index c3dbc8cd76..3f70677ba6 100644
--- a/lib/arel/engines/sql/core_extensions/nil_class.rb
+++ b/lib/arel/engines/sql/core_extensions/nil_class.rb
@@ -5,6 +5,10 @@ module Arel
         'IS'
       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 9f15dff771..b71ef29fd5 100644
--- a/lib/arel/engines/sql/core_extensions/object.rb
+++ b/lib/arel/engines/sql/core_extensions/object.rb
@@ -9,6 +9,10 @@ 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 3756231a46..e40240eec5 100644
--- a/lib/arel/engines/sql/predicates.rb
+++ b/lib/arel/engines/sql/predicates.rb
@@ -27,7 +27,9 @@ module Arel
     end
 
     class Not < Binary
-      def predicate_sql; '!=' end
+      def predicate_sql
+        operand2.not_predicate_sql
+      end
     end
 
     class GreaterThanOrEqualTo < Binary
diff --git a/lib/arel/engines/sql/primitives.rb b/lib/arel/engines/sql/primitives.rb
index 666579331a..78e1ed7f0b 100644
--- a/lib/arel/engines/sql/primitives.rb
+++ b/lib/arel/engines/sql/primitives.rb
@@ -34,6 +34,10 @@ module Arel
       value.equality_predicate_sql
     end
 
+    def not_predicate_sql
+      value.not_predicate_sql
+    end
+
     def to_sql(formatter = Sql::WhereCondition.new(relation))
       formatter.value value
     end