From 7b445c6dd578277f7313746fc497429a56e4b43c Mon Sep 17 00:00:00 2001
From: Brian Cardarella <bcardarella@gmail.com>
Date: Sun, 23 Jan 2011 11:54:00 -0500
Subject: Added MINUS for Oracle Aliased :minus to :except for the
 SelectManager

---
 lib/arel/select_manager.rb   | 1 +
 lib/arel/visitors/oracle.rb  | 4 ++++
 test/visitors/test_oracle.rb | 9 +++++++++
 3 files changed, 14 insertions(+)

diff --git a/lib/arel/select_manager.rb b/lib/arel/select_manager.rb
index 77853ea854..0fa344945e 100644
--- a/lib/arel/select_manager.rb
+++ b/lib/arel/select_manager.rb
@@ -152,6 +152,7 @@ module Arel
     def except other
       Nodes::Except.new ast, other.ast
     end
+    alias :minus :except
 
     def with *subqueries
       if subqueries.first.is_a? Symbol
diff --git a/lib/arel/visitors/oracle.rb b/lib/arel/visitors/oracle.rb
index aaf0324fd7..3beea287a6 100644
--- a/lib/arel/visitors/oracle.rb
+++ b/lib/arel/visitors/oracle.rb
@@ -61,6 +61,10 @@ module Arel
         "raw_rnum_ > #{visit o.expr}"
       end
 
+      def visit_Arel_Nodes_Except o
+        "( #{visit o.left} MINUS #{visit o.right} )"
+      end
+
       ###
       # Hacks for the order clauses specific to Oracle
       def order_hacks o
diff --git a/test/visitors/test_oracle.rb b/test/visitors/test_oracle.rb
index c6fcb7134c..87b94409e3 100644
--- a/test/visitors/test_oracle.rb
+++ b/test/visitors/test_oracle.rb
@@ -134,6 +134,15 @@ module Arel
         end
 
       end
+
+      it 'modified except to be minus' do
+        left = Nodes::SqlLiteral.new("SELECT * FROM users WHERE age > 10")
+        right = Nodes::SqlLiteral.new("SELECT * FROM users WHERE age > 20")
+        sql = @visitor.accept Nodes::Except.new(left, right)
+        sql.must_be_like %{
+          ( SELECT * FROM users WHERE age > 10 MINUS SELECT * FROM users WHERE age > 20 )
+        }
+      end
     end
   end
 end
-- 
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