谢谢你的阅读。我对sql有一些经验，对python非常陌生。
在下面的代码中，我正在访问Python2.7中的两个数据库，连接工作正常。我可以在一个语句中查询具有设备序列号的表，没有问题。然后我想在另一个数据库中查询一个名称与序列号匹配的表，提取“stamp”字段的最新值。当我明确地将表命名为ccnbsc00000001时，所有这些都可以工作，但是当使用变量替代时，它失败了。
当替换可变电流装置时，包括额外字符。当我打印这个变量时，这些字符不会出现在输出中。下面是代码，错误结果在底部

# !/usr/bin/python

### Imports

import datetime
import mysql.connector

# Connect to heartbeat results database

hb_db = mysql.connector.connect(
  host="localhost",
  user="otheruser",
  passwd="******",
  database="active_devices"
)

# Connect to heartbeat results database

device_Settings_db = mysql.connector.connect(
  host="localhost",
  user="otheruser",
  passwd="******",
  database="active_devices"
)
device_settings_cursor = device_settings_db.cursor()
hb_cursor = hb_db.cursor()

## Get deviuce serial#

device_settings_cursor.execute('select device_serial from devices')
active_devices = device_settings_cursor.fetchall()
print ("these are the current devices:")
print (active_devices)
for device in active_devices:

 currentdevice = device[0]
 print(currentdevice)

 print ("SELECT MAX(stamp) FROM (%s)" , (currentdevice,) )
 hb_cursor.execute('SELECT MAX(stamp) FROM (%s)' , (currentdevice,) )

 laststamp = hb_cursor.fetchone
 laststamp = laststamp[0]
 print("Last time stamp is:")
 print(laststamp)

* 

打印输出（有源设备）[（u'ccnbsc00000001'，），（u'ccnbsc00000002'，）]
打印输出（currentdevice）ccnbsc00000001（这是正确的输出/值）
但是我在sql查询中得到了这个错误，这意味着它保留了周围的字符'and'）

Traceback (most recent call last):
  File "./hb_notify.py", line 61, in <module>
    hb_cursor.execute('SELECT MAX(stamp) FROM (%s)' , (currentccn,) )
  File "/usr/lib/python2.7/site-packages/mysql/connector/cursor.py", line 551, in execute
self._handle_result(self._connection.cmd_query(stmt))
  File "/usr/lib/python2.7/site-packages/mysql/connector/connection.py", line 490, in cmd_query
  result = self._handle_result(self._send_cmd(ServerCmd.QUERY, query))
File "/usr/lib/python2.7/site-packages/mysql/connector/connection.py", line 395, in _handle_result
  raise errors.get_exception(packet)
mysql.connector.errors.ProgrammingError: 1064 (42000): You have an error in your**SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near ''ccnbsc00000001')' at line 1**