Index: lib/sqlalchemy/sql.py
===================================================================
--- lib/sqlalchemy/sql.py	(revision 1441)
+++ lib/sqlalchemy/sql.py	(working copy)
@@ -13,7 +13,7 @@
 import string, re, random
 types = __import__('types')
 
-__all__ = ['text', 'table', 'column', 'func', 'select', 'update', 'insert', 'delete', 'join', 'and_', 'or_', 'not_', 'between_', 'cast', 'union', 'union_all', 'null', 'desc', 'asc', 'outerjoin', 'alias', 'subquery', 'literal', 'bindparam', 'exists']
+__all__ = ['text', 'table', 'column', 'func', 'select', 'update', 'insert', 'delete', 'join', 'and_', 'or_', 'not_', 'between_', 'case', 'cast', 'union', 'union_all', 'null', 'desc', 'asc', 'outerjoin', 'alias', 'subquery', 'literal', 'bindparam', 'exists']
 
 def desc(column):
     """returns a descending ORDER BY clause element, e.g.:
@@ -132,6 +132,17 @@
     """ returns BETWEEN predicate clause (clausetest BETWEEN clauseleft AND clauseright) """
     return BooleanExpression(ctest, and_(cleft, cright), 'BETWEEN')
 between = between_
+
+def case(whens, value=None, else_=None):
+    """ SQL CASE statement -- whens are a sequence of pairs to be translated into "when / then" clauses;
+        optional [value] for simple case statements, and [else_] for case defaults """
+    whenlist = [CompoundClause(None, 'WHEN', c, 'THEN', r) for (c,r) in whens]
+    if else_:
+        whenlist.append(CompoundClause(None, 'ELSE', else_))
+    cc = CompoundClause(None, 'CASE', value, *whenlist + ['END'])
+    for c in cc.clauses:
+        c.parens = False
+    return cc
    
 def cast(clause, totype, **kwargs):
     """ returns CAST function CAST(clause AS totype)