python3 操作MYSQL实例及异常信息处理--用traceback模块

# 用traceback模块查看异常
import traceback
import pymysql

db = pymysql.connect(host='localhost', user='root', password='root', port=3306, db='spiders')
cursor = db.cursor()

try:
    sql = 'SELECT graph, brand_name FROM base_info'
    # 执行sql语句
    cursor.execute(sql)
    result = cursor.fetchone()
except:
    # 输出异常信息
    traceback.print_exc()
    # 如果发生异常，则回滚
    db.rollback()
finally:
    # 最终关闭数据库连接
    db.close()