关于元组的新手Python问题

我是Python新手,正在使用 cx_Oracle cx_Oracle documentation 他们有这样一个代码示例:

import sys
import cx_Oracle

connection = cx_Oracle.Connection("user/pw@tns")
cursor = connection.cursor()

try:
    cursor.execute("select 1 / 0 from dual")
except cx_Oracle.DatabaseError, exc:
    error, = exc.args
    print >> sys.stderr, "Oracle-Error-Code:", error.code
    print >> sys.stderr, "Oracle-Error-Message:", error.message

, =

我知道exc.args是一个单元组,但我就是不明白“ , = AttributeError: 'tuple' object has no attribute 'code' ".

编辑:

无需解包元组即可完成此操作:

import sys
import cx_Oracle

connection = cx_Oracle.Connection("user/pw@tns")
cursor = connection.cursor()

try:
    cursor.execute("select 1 / 0 from dual")
except cx_Oracle.DatabaseError, exc:
    print >> sys.stderr, "Oracle-Error-Code:", exc.args[0].code
    print >> sys.stderr, "Oracle-Error-Message:", exc.args[0].message