MySQLdb 防SQL注入，同时打印已执行的SQL

>>> import MySQLdb
>>> conn=MySQLdb.connect(user='root',passwd='root')
>>> cur=conn.cursor()
>>> sql = "select user from mysql.user where user='%s' and password = '%s' ";
>>> cur.execute(sql % ('aaa','aaa'))
0L
>>> cur.execute(sql % ("aaa","aaa' or '' ='")) #SQL注入
3L
>>> cur._executed #打印刚执行的SQL
"select user from mysql.user where user='aaa' and password = 'aaa' or '' ='' "
>>> cur.fetchall()
(('root',), ('root',), ('root',))
>>> sql="select user from mysql.user where user=%s and password = %s "
>>> cur.execute(sql,("aaa","aaa' or '' ='")) #SQL注入失败。将变量作为 execute 的参数传入，execute函数会自动进行转义，需要注意的是，所有的占位符都是%s, %s 两边不需要引号，execute会自动根据你传如参数的类型判断是否添加引号。
0L
>>> cur._executed
"select user from mysql.user where user='aaa' and password = 'aaa\\' or \\'\\' =\\'' "