fixed union() bug whereby oid_column would not be available if no oid_column in embedded selects

3 files changed, 18 insertions, 3 deletions

diff --git a/CHANGES b/CHANGES
index f66bc798c..b0fbbc801 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,7 +1,12 @@
 =======
 CHANGES
 =======
-
+0.4.6
+=====
+- sql
+    - Fixed bug with union() when applied to non-Table connected
+      select statements
+      
 0.4.5
 =====
 - orm
diff --git a/lib/sqlalchemy/sql/expression.py b/lib/sqlalchemy/sql/expression.py
index 9272e6d82..2ed3b372f 100644
--- a/lib/sqlalchemy/sql/expression.py
+++ b/lib/sqlalchemy/sql/expression.py
@@ -2993,11 +2993,14 @@ class CompoundSelect(_SelectBaseMixin, FromClause):
                 self.selects.append(s)
 
         _SelectBaseMixin.__init__(self, **kwargs)
-
+        
+        self.oid_column = None
         for s in self.selects:
+            # TODO: need to repair proxy_column here to 
+            # not require full traversal
             if s.oid_column:
                 self.oid_column = self._proxy_column(s.oid_column)
-
+    
     def self_group(self, against=None):
         return _FromGrouping(self)
 
diff --git a/test/sql/select.py b/test/sql/select.py
index 06679e956..77926b421 100644
--- a/test/sql/select.py
+++ b/test/sql/select.py
@@ -888,6 +888,13 @@ SELECT thirdtable.userid FROM thirdtable)"
             "SELECT myothertable.otherid FROM myothertable EXCEPT SELECT thirdtable.userid FROM thirdtable \
 UNION SELECT mytable.myid FROM mytable"
         )
+        
+        # test unions working with non-oid selectables
+        s = select([column('foo'), column('bar')])
+        s = union(s, s)
+        s = union(s, s)
+        self.assert_compile(s, "SELECT foo, bar UNION SELECT foo, bar UNION (SELECT foo, bar UNION SELECT foo, bar)")
+        
 
     @testing.uses_deprecated('//get_params')
     def test_binds(self):