6 files changed, 61 insertions, 12 deletions
diff --git a/lib/active_relation.rb b/lib/active_relation.rb
index cdac17facb..0b55ed74d0 100644
--- a/lib/active_relation.rb
+++ b/lib/active_relation.rb
@@ -6,5 +6,6 @@ require 'activerecord'
 
 require 'active_relation/sql_builder'
 require 'active_relation/extensions'
+require 'active_relation/predicates'
 require 'active_relation/relations'
-require 'active_relation/predicates'
-\ No newline at end of file
+require 'active_relation/primitives'
+\ No newline at end of file
diff --git a/lib/active_relation/primitives.rb b/lib/active_relation/primitives.rb
new file mode 100644
index 0000000000..5d35f42564
--- /dev/null
+++ b/lib/active_relation/primitives.rb
@@ -0,0 +1,3 @@
+require 'active_relation/primitives/attribute'
+require 'active_relation/primitives/aggregation'
+
diff --git a/lib/active_relation/primitives/aggregation.rb b/lib/active_relation/primitives/aggregation.rb
new file mode 100644
index 0000000000..20fdcf46c5
--- /dev/null
+++ b/lib/active_relation/primitives/aggregation.rb
@@ -0,0 +1,21 @@
+module ActiveRelation
+  module Primitives
+    class Aggregation
+      include SqlBuilder
+  
+      attr_reader :attribute, :function_sql
+      
+      def initialize(attribute, function_sql)
+        @attribute, @function_sql = attribute, function_sql
+      end
+  
+      def to_sql(options = {})
+        "#{function_sql}(@attribute.to_sql)"
+      end
+      
+      def ==(other)
+        self.class == other.class and attribute == other.attribute and function_sql == other.function_sql
+      end
+    end
+  end
+end
+\ No newline at end of file
diff --git a/lib/active_relation/relations/attribute.rb b/lib/active_relation/primitives/attribute.rb
index 2fe702cb14..65ae12cf36 100644
--- a/lib/active_relation/relations/attribute.rb
+++ b/lib/active_relation/primitives/attribute.rb
@@ -1,7 +1,7 @@
 module ActiveRelation
   module Primitives
     class Attribute
-      include ::ActiveRelation::SqlBuilder
+      include SqlBuilder
   
       attr_reader :relation, :name, :alias
   
@@ -10,7 +10,7 @@ module ActiveRelation
       end
   
       def alias(aliaz = nil)
-        aliaz ? ActiveRelation::Primitives::Attribute.new(relation, name, aliaz) : @alias
+        aliaz ? Attribute.new(relation, name, aliaz) : @alias
       end
   
       def qualified_name
@@ -25,32 +25,57 @@ module ActiveRelation
         relation == other.relation and name == other.name and @alias == other.alias
       end
 
-      module Predications  
+      module Predications
+        include Predicates
+        
         def equals(other)
-          Predicates::Equality.new(self, other)
+          Equality.new(self, other)
         end
   
         def less_than(other)
-          Predicates::LessThan.new(self, other)
+          LessThan.new(self, other)
         end
   
         def less_than_or_equal_to(other)
-          Predicates::LessThanOrEqualTo.new(self, other)
+          LessThanOrEqualTo.new(self, other)
         end
   
         def greater_than(other)
-          Predicates::GreaterThan.new(self, other)
+          GreaterThan.new(self, other)
         end
   
         def greater_than_or_equal_to(other)
-          Predicates::GreaterThanOrEqualTo.new(self, other)
+          GreaterThanOrEqualTo.new(self, other)
         end
   
         def matches(regexp)
-          Predicates::Match.new(self, regexp)
+          Match.new(self, regexp)
         end
       end
       include Predications
+      
+      module Aggregations
+        def count
+          Aggregation.new(self, "COUNT")
+        end
+        
+        def sum
+          Aggregation.new(self, "SUM")
+        end
+        
+        def maximum
+          Aggregation.new(self, "MAX")
+        end
+        
+        def minimum
+          Aggregation.new(self, "MIN")
+        end
+        
+        def average
+          Aggregation.new(self, "AVG")
+        end
+      end
+      include Aggregations
   
       def to_sql(options = {})
         "#{quote_table_name(relation.table)}.#{quote_column_name(name)}" + (options[:use_alias] && self.alias ? " AS #{self.alias.to_s.to_sql}" : "")
diff --git a/lib/active_relation/relations.rb b/lib/active_relation/relations.rb
index f7d1bc207a..a25e82f607 100644
--- a/lib/active_relation/relations.rb
+++ b/lib/active_relation/relations.rb
@@ -2,7 +2,6 @@ require 'active_relation/relations/base'
 require 'active_relation/relations/compound'
 require 'active_relation/relations/table'
 require 'active_relation/relations/join'
-require 'active_relation/relations/attribute'
 require 'active_relation/relations/projection'
 require 'active_relation/relations/selection'
 require 'active_relation/relations/order'
diff --git a/lib/active_relation/relations/table.rb b/lib/active_relation/relations/table.rb
index 38f540cc52..d642851687 100644
--- a/lib/active_relation/relations/table.rb
+++ b/lib/active_relation/relations/table.rb
@@ -23,7 +23,7 @@ module ActiveRelation
       private
       def attributes_by_name
         @attributes_by_name ||= connection.columns(table, "#{table} Columns").inject({}) do |attributes_by_name, column|
-          attributes_by_name.merge(column.name => ActiveRelation::Primitives::Attribute.new(self, column.name.to_sym))
+          attributes_by_name.merge(column.name => Primitives::Attribute.new(self, column.name.to_sym))
         end
       end