In order to support a <null> type column being returned from

engine.  A TypeObject is needed instead of returning None.  As
None is used to verify that the type returned is in the TYPEMAP.

cursor.execute('select NULL from DUAL')

fails without this change.  I don't know how TypeObject is used an rather
there is a side-effect by using TypeObject(None) and any use of TypeObject.

Author: butson

pynuodb/datatype.py

@@ -154,8 +154,9 @@ def __cmp__(self, other):
 NUMBER = TypeObject(int, decimal.Decimal)
 DATETIME = TypeObject(Timestamp, Date, Time)
 ROWID = TypeObject()
+NULL = TypeObject(None)
 
-TYPEMAP = {"<null>": None,
+TYPEMAP = {"<null>": NULL,
            "string": STRING,
            "char": STRING,
            "varchar": STRING,