1 files changed, 51 insertions, 33 deletions

diff --git a/lib/sqlalchemy/sql.py b/lib/sqlalchemy/sql.py
index 6322b9522..3ab1e5ec2 100644
--- a/lib/sqlalchemy/sql.py
+++ b/lib/sqlalchemy/sql.py
@@ -259,8 +259,43 @@ class ClauseElement(object):
     def result(self, **params):
         """the same as execute(), except a RowProxy object is returned instead of a DBAPI cursor."""
         raise NotImplementedError()
+
+class CompareMixin(object):
+    def __lt__(self, other):
+        return self._compare('<', other)
         
-class ColumnClause(ClauseElement):
+    def __le__(self, other):
+        return self._compare('<=', other)
+
+    def __eq__(self, other):
+        return self._compare('=', other)
+
+    def __ne__(self, other):
+        return self._compare('!=', other)
+
+    def __gt__(self, other):
+        return self._compare('>', other)
+
+    def __ge__(self, other):
+        return self._compare('>=', other)
+
+    def like(self, other):
+        return self._compare('LIKE', other)
+
+    def in_(self, *other):
+        if _is_literal(other[0]):
+            return self._compare('IN', CompoundClause(',', other))
+        else:
+            return self._compare('IN', union(*other))
+
+    def startswith(self, other):
+        return self._compare('LIKE', str(other) + "%")
+    
+    def endswith(self, other):
+        return self._compare('LIKE', "%" + str(other))
+
+        
+class ColumnClause(ClauseElement, CompareMixin):
     """represents a textual column clause in a SQL statement."""
 
     def __init__(self, text, selectable):
@@ -284,6 +319,19 @@ class ColumnClause(ClauseElement):
     def _get_from_objects(self):
         return []
 
+    def _compare(self, operator, obj):
+        if _is_literal(obj):
+            if obj is None:
+                if operator != '=':
+                    raise "Only '=' operator can be used with NULL"
+                return BinaryClause(self, null(), 'IS')
+            elif self.table.name is None:
+                obj = BindParamClause(self.text, obj, shortname=self.text, type=self.type)
+            else:
+                obj = BindParamClause(self.table.name + "_" + self.text, obj, shortname = self.text, type=self.type)
+
+        return BinaryClause(self, obj, operator)
+
     def _make_proxy(self, selectable, name = None):
         c = ColumnClause(self.text or name, selectable)
         selectable.columns[c.key] = c
@@ -525,7 +573,8 @@ class Alias(Selectable):
         return select([self], whereclauses, **params)
 
 
-class ColumnSelectable(Selectable):
+
+class ColumnSelectable(Selectable, CompareMixin):
     """Selectable implementation that gets attached to a schema.Column object."""
     
     def __init__(self, column):
@@ -562,39 +611,8 @@ class ColumnSelectable(Selectable):
 
         return BinaryClause(self.column, obj, operator)
 
-    def __lt__(self, other):
-        return self._compare('<', other)
-        
-    def __le__(self, other):
-        return self._compare('<=', other)
 
-    def __eq__(self, other):
-        return self._compare('=', other)
-
-    def __ne__(self, other):
-        return self._compare('!=', other)
-
-    def __gt__(self, other):
-        return self._compare('>', other)
 
-    def __ge__(self, other):
-        return self._compare('>=', other)
-
-    def like(self, other):
-        return self._compare('LIKE', other)
-
-    def in_(self, *other):
-        if _is_literal(other[0]):
-            return self._compare('IN', CompoundClause(',', other))
-        else:
-            return self._compare('IN', union(*other))
-
-    def startswith(self, other):
-        return self._compare('LIKE', str(other) + "%")
-    
-    def endswith(self, other):
-        return self._compare('LIKE', "%" + str(other))
-        
 class TableImpl(Selectable):
     """attached to a schema.Table to provide it with a Selectable interface
     as well as other functions