fixed AttributeError: 'Expression' object has no attribute '_table' issue

VERSION

@@ -1 +1 @@
-Version 2.0.2 (2012-08-30 08:31:49) stable
+Version 2.0.2 (2012-08-30 14:42:29) stable

gluon/dal.py

@@ -7935,6 +7935,7 @@ class Expression(object):
         self.op = op
         self.first = first
         self.second = second
+        self._table = getattr(first,'_table',None)
         ### self._tablename =  first._tablename ## CHECK
         if not type and first and hasattr(first,'type'):
             self.type = first.type

gluon/tests/test_dal.py

@@ -411,12 +411,14 @@ class TestMinMaxSum(unittest.TestCase):
         self.assertEqual(db.t.insert(a=3), 3)
         s = db.t.a.min()
         self.assertEqual(db(db.t.id > 0).select(s)[0]._extra[s], 1)
+        self.assertEqual(db(db.t.id > 0).select(s).first()[s], 1)
+        self.assertEqual(db().select(s).first()[s], 1)
         s = db.t.a.max()
-        self.assertEqual(db(db.t.id > 0).select(s)[0]._extra[s], 3)
+        self.assertEqual(db().select(s).first()[s], 3)
         s = db.t.a.sum()
-        self.assertEqual(db(db.t.id > 0).select(s)[0]._extra[s], 6)
+        self.assertEqual(db().select(s).first()[s], 6)
         s = db.t.a.count()
-        self.assertEqual(db(db.t.id > 0).select(s)[0]._extra[s], 3)
+        self.assertEqual(db().select(s).first()[s], 3)
         db.t.drop()