1 files changed, 2 insertions, 2 deletions
diff --git a/activerecord/lib/active_record/relation/calculations.rb b/activerecord/lib/active_record/relation/calculations.rb
index 7c43d844d0..a7d2f4bd24 100644
--- a/activerecord/lib/active_record/relation/calculations.rb
+++ b/activerecord/lib/active_record/relation/calculations.rb
@@ -343,13 +343,13 @@ module ActiveRecord
 
     def column_for(field)
       field_name = field.respond_to?(:name) ? field.name.to_s : field.to_s.split('.').last
-      @klass.columns.detect { |c| c.name.to_s == field_name }
+      @klass.columns_hash[field_name]
     end
 
     def type_cast_calculated_value(value, column, operation = nil)
       case operation
         when 'count'   then value.to_i
-        when 'sum'     then type_cast_using_column(value || '0', column)
+        when 'sum'     then type_cast_using_column(value || 0, column)
         when 'average' then value.respond_to?(:to_d) ? value.to_d : value
         else type_cast_using_column(value, column)
       end