用python如何导出数据库数据

import pymysql

host, user, passwd, db='127.0.0.1','root','123','xxx'

    conn = pymysql.connect(user=user,host=host,port=3306,passwd=passwd,db=db,charset='utf8')

cur = conn.cursor()

sql = 'select * from %s' % table_name

cur.execute(sql)  # 返回受影响的行数

fields = [field[0] for field in cur.description]  # 获取所有字段名

all_data = cur.fetchall()  # 所有数据