joins

2 files changed, 26 insertions, 5 deletions

diff --git a/lib/sql_algebra/relations/join_operation.rb b/lib/sql_algebra/relations/join_operation.rb
index dab8e9e6bd..2b4548a041 100644
--- a/lib/sql_algebra/relations/join_operation.rb
+++ b/lib/sql_algebra/relations/join_operation.rb
@@ -6,7 +6,7 @@ class JoinOperation
   end
   
   def on(*predicates)
-    JoinRelation.new(relation1, relation2, *predicates)
+    relation_class.new(relation1, relation2, *predicates)
   end
   
   def ==(other)
diff --git a/lib/sql_algebra/relations/relation.rb b/lib/sql_algebra/relations/relation.rb
index f1f8fc5884..bd812b368d 100644
--- a/lib/sql_algebra/relations/relation.rb
+++ b/lib/sql_algebra/relations/relation.rb
@@ -1,13 +1,34 @@
 class Relation
-  def *(other)
-    JoinOperation.new(self, other)
+  def <=>(other)
+    InnerJoinOperation.new(self, other)
   end
   
-  def [](attribute_name)
-    Attribute.new(self, attribute_name)
+  def <<(other)
+    LeftOuterJoinOperation.new(self, other)
+  end
+  
+  def [](index)
+    case index
+    when Symbol
+      Attribute.new(self, index)
+    when Range
+      RangeRelation.new(self, index)
+    end
   end
   
   def include?(attribute)
     RelationInclusionPredicate.new(attribute, self)
   end
+  
+  def select(*predicates)
+    SelectionRelation.new(self, *predicates)
+  end
+  
+  def project(*attributes)
+    ProjectionRelation.new(self, *attributes)
+  end
+  
+  def order(*attributes)
+    OrderRelation.new(self, *attributes)
+  end
 end
\ No newline at end of file