Added DISTINCT support. Modified when to quote or not columns and tables.

4 files changed, 26 insertions, 7 deletions

diff --git a/lib/arel/primitives/attribute.rb b/lib/arel/primitives/attribute.rb
index 7021e9f9ed..6cb558d8ce 100644
--- a/lib/arel/primitives/attribute.rb
+++ b/lib/arel/primitives/attribute.rb
@@ -120,8 +120,8 @@ module Arel
     include Predications
 
     module Expressions
-      def count
-        Expression.new(self, "COUNT")
+      def count(distinct = false)
+        distinct ?  Expression.new(self, "DISTINCT").count :  Expression.new(self, "COUNT")
       end
 
       def sum
diff --git a/lib/arel/primitives/value.rb b/lib/arel/primitives/value.rb
index 36a7fb7c71..9c6e518a95 100644
--- a/lib/arel/primitives/value.rb
+++ b/lib/arel/primitives/value.rb
@@ -6,7 +6,11 @@ module Arel
 
 
     def to_sql(formatter = Sql::WhereCondition.new(relation))
-      formatter.value value
+      if value =~ /^\(.*\)$/
+        value
+      else
+        formatter.value value
+      end
     end
 
     def format(object)
diff --git a/lib/arel/relations/relation.rb b/lib/arel/relations/relation.rb
index 986bc3fbeb..50c46aa2ed 100644
--- a/lib/arel/relations/relation.rb
+++ b/lib/arel/relations/relation.rb
@@ -1,5 +1,7 @@
 module Arel
   class Relation
+    attr_reader :count
+
     def session
       Session.new
     end
@@ -12,6 +14,11 @@ module Arel
       engine.select_values self.to_sql
     end
 
+    def count
+      @count = "COUNT(*) AS count_all"
+      engine.select_value self.to_sql
+    end
+
     def to_sql(formatter = Sql::SelectStatement.new(self))
       formatter.select select_sql, self
     end
@@ -19,7 +26,7 @@ module Arel
 
     def select_sql
       [
-        "SELECT     #{attributes.collect { |a| a.to_sql(Sql::SelectClause.new(self)) }.join(', ')}",
+        "SELECT  #{@count} #{attributes.collect { |a| a.to_sql(Sql::SelectClause.new(self)) }.join(', ') unless @count}",
         "FROM       #{table_sql(Sql::TableReference.new(self))}",
         (joins(self)                                                                                    unless joins(self).blank? ),
         ("WHERE     #{wheres   .collect { |w| w.to_sql(Sql::WhereClause.new(self)) }.join("\n\tAND ")}" unless wheres.blank?      ),
diff --git a/lib/arel/sql/formatters.rb b/lib/arel/sql/formatters.rb
index f105fbea72..aa10952d04 100644
--- a/lib/arel/sql/formatters.rb
+++ b/lib/arel/sql/formatters.rb
@@ -15,14 +15,18 @@ module Arel
       def attribute(attribute)
         # FIXME this should check that the column exists
         if attribute.name.to_s =~ /^\w*$/
-        "#{quote_table_name(name_for(attribute.original_relation))}.#{quote_column_name(attribute.name)}" + (attribute.alias ? " AS #{quote(attribute.alias.to_s)}" : "")
+          "#{quote_table_name(name_for(attribute.original_relation))}.#{quote_column_name(attribute.name)}" + (attribute.alias ? " AS #{quote(attribute.alias.to_s)}" : "")
         else
           attribute.name.to_s + (attribute.alias ? " AS #{quote(attribute.alias.to_s)}" : "")
         end
       end
 
       def expression(expression)
-        "#{expression.function_sql}(#{expression.attribute.to_sql(self)})" + (expression.alias ? " AS #{quote_column_name(expression.alias)}" : '')
+        if expression.function_sql == "DISTINCT"
+          "#{expression.function_sql} #{expression.attribute.to_sql(self)}" + (expression.alias ? " AS #{quote_column_name(expression.alias)}" : '')
+        else
+          "#{expression.function_sql}(#{expression.attribute.to_sql(self)})" + (expression.alias ? " AS #{quote_column_name(expression.alias)}" : '')
+        end
       end
 
       def select(select_sql, table)
@@ -89,7 +93,11 @@ module Arel
       end
 
       def table(table)
-        quote_table_name(table.name) + (table.name != name_for(table) ? " AS " + quote_table_name(name_for(table)) : '')
+        if table.name =~ /^(\w|-)*$/
+          quote_table_name(table.name) + (table.name != name_for(table) ? " AS " + quote_table_name(name_for(table)) : '')
+        else
+          table.name + (table.name != name_for(table) ? " AS " + (name_for(table)) : '')
+        end
       end
     end