【python】cursor.fetchall()操作后导致的No result set to fetch from

新人学习python。学习慕课网的python操作mysql课程。https://www.imooc.com/video/9219

然后进行都最后发现，卡在了扣钱上面，会显示No result set to fetch from。

以下是源码：

# -$- coding:utf-8 -*- """ @author:Zhang @file:transfer_money.py @time:2018-02-19 1:48 """ import sys import mysql.connector class TransferMoney(object): def __init__(self,conn): self.conn = conn def check_acct_available(self,accid): try: cursor = self.conn.cursor() sql = "SELECT * FROM account WHERE accid=%s" % accid cursor.execute(sql) print("check_acct_available:" + sql) rs = cursor.fetchall() if len(rs)!=1: raise Exception("账号%s不存在" % accid) finally: cursor.close() def has_enough_money(self,accid,money): try: cursor = self.conn.cursor() sql = "SELECT * FROM account WHERE accid=%s and money>%s" % (accid,money) cursor.execute(sql) print("has_enough_money:" + sql) rs = cursor.fetchall() if len(rs) != 1: raise Exception("账号%s没有足够钱" % accid) finally: cursor.close() def redue_money(self,accid,money): try: cursor = self.conn.cursor() sql = "UPDATE account SET money=money-%s WHERE accid=%s" % (money,accid) cursor.execute(sql) print("reduce_money:" + sql) rs = cursor.fetchall() if cursor.rowcount != 1: raise Exception("账号%s减款失败" % accid) finally: cursor.close() def add_money(self,accid,money): try: cursor = self.conn.cursor() sql = "UPDATE account SET money=money+%s WHERE accid=%s" % (money,accid) cursor.execute(sql) print("add_money:" + sql) rs = cursor.fetchall() if cursor.rowcount != 1: raise Exception("账号%s加款失败" % accid) finally: cursor.close() def transfer(self,souce_accid,target_accid,money): try: self.check_acct_available(source_accid) self.check_acct_available(target_accid) self.has_enough_money(source_accid,money) # 以上检验都成功的话 self.redue_money(source_accid,money) self.add_money(target_accid,money) self.conn.commit() except Exception as e: self.conn.rollback() raise e if __name__ == "__main__": source_accid = sys.argv[1] target_accid = sys.argv[2] money = sys.argv[3] conn = mysql.connector.connect(host="127.0.0.1",user="root",password="password",port=3306,db="test") tr_money = TransferMoney(conn) try: tr_money.transfer(source_accid,target_accid,money) except Exception as e: print("出现问题："+str(e)) finally: conn.close()

我发现问题在于，是python操作mysql抛出unread result from。

然后我就先把

rs = cursor.fetchall()

给注释掉..或者改成 cursor.fetchone() 就能顺利运行了。

还不知道本质原理，但是方法先放着。弄清楚了回来补上。