diff --git a/www/orm.py b/www/orm.py
index 93ea5b4..3ec939a 100644
--- a/www/orm.py
+++ b/www/orm.py
@@ -7,8 +7,8 @@
 
 import aiomysql
 
-def log(sql, args=()):
-    logging.info('SQL: %s' % sql)
+def log(sql, args=[]):
+    logging.info('SQL: [%s] args: %s' % (sql, args))
 
 async def create_pool(loop, **kw):
     logging.info('create database connection pool...')
@@ -40,7 +40,7 @@ async def select(sql, args, size=None):
         return rs
 
 async def execute(sql, args, autocommit=True):
-    log(sql)
+    log(sql, args)
     async with __pool.get() as conn:
         if not autocommit:
             await conn.begin()
@@ -56,12 +56,6 @@ async def execute(sql, args, autocommit=True):
             raise
         return affected
 
-def create_args_string(num):
-    L = []
-    for n in range(num):
-        L.append('?')
-    return ', '.join(L)
-
 class Field(object):
 
     def __init__(self, name, column_type, primary_key, default):
@@ -103,34 +97,32 @@ class ModelMetaclass(type):
     def __new__(cls, name, bases, attrs):
         if name=='Model':
             return type.__new__(cls, name, bases, attrs)
-        tableName = attrs.get('__table__', None) or name
+        tableName = attrs.get('__table__', name)
         logging.info('found model: %s (table: %s)' % (name, tableName))
         mappings = dict()
-        fields = []
+        escaped_fields = []
         primaryKey = None
-        for k, v in attrs.items():
+        for k, v in attrs.copy().items():
             if isinstance(v, Field):
                 logging.info('  found mapping: %s ==> %s' % (k, v))
-                mappings[k] = v
+                mappings[k] = attrs.pop(k)
                 if v.primary_key:
                     # 找到主键:
                     if primaryKey:
                         raise StandardError('Duplicate primary key for field: %s' % k)
                     primaryKey = k
                 else:
-                    fields.append(k)
+                    escaped_fields.append(k)
         if not primaryKey:
             raise StandardError('Primary key not found.')
-        for k in mappings.keys():
-            attrs.pop(k)
-        escaped_fields = list(map(lambda f: '`%s`' % f, fields))
+
         attrs['__mappings__'] = mappings # 保存属性和列的映射关系
         attrs['__table__'] = tableName
         attrs['__primary_key__'] = primaryKey # 主键属性名
-        attrs['__fields__'] = fields # 除主键外的属性名
-        attrs['__select__'] = 'select `%s`, %s from `%s`' % (primaryKey, ', '.join(escaped_fields), tableName)
-        attrs['__insert__'] = 'insert into `%s` (%s, `%s`) values (%s)' % (tableName, ', '.join(escaped_fields), primaryKey, create_args_string(len(escaped_fields) + 1))
-        attrs['__update__'] = 'update `%s` set %s where `%s`=?' % (tableName, ', '.join(map(lambda f: '`%s`=?' % (mappings.get(f).name or f), fields)), primaryKey)
+        attrs['__fields__'] = escaped_fields + [primaryKey] # 全部属性名，主键一定在是最后
+        attrs['__select__'] = 'select * from `%s`' % (tableName)
+        attrs['__insert__'] = 'insert into `%s` (%s) values (%s)' % (tableName, ', '.join('`%s`' % f for f in attrs['__fields__']), ', '.join('?' * len(mappings)))
+        attrs['__update__'] = 'update `%s` set %s where `%s`=?' % (tableName, ', '.join('`%s`=?' % f for f in escaped_fields), primaryKey)
         attrs['__delete__'] = 'delete from `%s` where `%s`=?' % (tableName, primaryKey)
         return type.__new__(cls, name, bases, attrs)
 
@@ -148,9 +140,6 @@ def __getattr__(self, key):
     def __setattr__(self, key, value):
         self[key] = value
 
-    def getValue(self, key):
-        return getattr(self, key, None)
-
     def getValueOrDefault(self, key):
         value = getattr(self, key, None)
         if value is None:
@@ -210,20 +199,18 @@ async def find(cls, pk):
 
     async def save(self):
         args = list(map(self.getValueOrDefault, self.__fields__))
-        args.append(self.getValueOrDefault(self.__primary_key__))
         rows = await execute(self.__insert__, args)
         if rows != 1:
             logging.warn('failed to insert record: affected rows: %s' % rows)
 
     async def update(self):
-        args = list(map(self.getValue, self.__fields__))
-        args.append(self.getValue(self.__primary_key__))
+        args = list(map(self.get, self.__fields__))
         rows = await execute(self.__update__, args)
         if rows != 1:
             logging.warn('failed to update by primary key: affected rows: %s' % rows)
 
     async def remove(self):
-        args = [self.getValue(self.__primary_key__)]
+        args = [self.get(self.__primary_key__)]
         rows = await execute(self.__delete__, args)
         if rows != 1:
             logging.warn('failed to remove by primary key: affected rows: %s' % rows)