#!/usr/bin/env python
#-*-coding:utf-8-*-
#异常处理，with的使用，
class Mycontex(object):def __init__(self,name):self.name=namedef __enter__(self):print("__enter__")return selfdef do_self(self):print('do_self')def __exit__(self,exc_type,exc_value,traceback):print('__exit__')print("Error: ",exc_type," info:",exc_value)if __name__=='__main__':with Mycontex('test context') as f:print(f.name)f.do_self()#!/usr/bin/env python
#-*-coding:utf-8-*-
import MySQLdb
#连接数据库
conn=MySQLdb.Connect(host='127.0.0.1',port=3306,user='root',passwd='123456',db='imooc',charset='utf8')
cursor=conn.cursor()sql_insert="insert into user(userid,username) values(10,'name10')"
sql_update="update user set username='name91' where userid=9"
sql_delete="delete from user where userid<3"
#异常处理
try:cursor.execute(sql_insert)print(cursor.rowcount)cursor.execute(sql_update)print(cursor.rowcount)cursor.execute(sql_delete)print(cursor.rowcount)conn.commit()
except Exception as e:print(e)#回滚事物conn.rollback()cursor.close()
conn.close()#!/usr/bin/env python
#-*-coding:utf-8-*
#银行转账模拟
import sys
import MySQLdbclass TransferMoney(object):def __init__(self,conn):self.conn=conn#检查用户是否存在def check_acct_available(self,acctid):cursor=self.conn.cursor()try:sql="select * from account where acctid=%s" % acctidcursor.execute(sql)print("check_acct_available:"+sql)rs=cursor.fetchall()if len(rs)!=1:raise Exception("账号%s不存在" % acctid)finally:cursor.close()#检查用户是否有足够的钱def has_enough_money(self,acctid,money):cursor=self.conn.cursor()try:sql="select * from account where acctid=%s and money>=%s" % (acctid,money)cursor.execute(sql)print("has_enough_money:"+sql)rs=cursor.fetchall()if len(rs)!=1:raise Exception("账号%s没有足够的钱" % acctid)finally:cursor.close()#用户减少的钱def reduce_money(self,acctid,money):cursor=self.conn.cursor()try:sql="update account set money=money-%s where acctid=%s" % (money,acctid)cursor.execute(sql)print("reduce_money:"+sql)if cursor.rowcount!=1:raise Exception("账号%s减款失败" % acctid)finally:cursor.close()def add_money(self,acctid,money):cursor=self.conn.cursor()try:sql="update account set money=money+%s where acctid=%s" % (money,acctid)cursor.execute(sql)print("add_money:"+sql)if cursor.rowcount!=1:raise Exception("账号%s加款失败" % acctid)finally:cursor.close()def transfer(self,source_acctid,target_acctid,money):try:self.check_acct_available(source_acctid)self.check_acct_available(target_acctid)self.has_enough_money(source_acctid,money)self.reduce_money(source_acctid,money)self.add_money(target_acctid,money)self.conn.commit()except Exception as e:self.conn.rollback()raise eif __name__=='__main__':#source_acctid=sys.argv[0]#target_acctid=sys.argv[1]#money=sys.argv[2]source_acctid=input('请输入用户')target_acctid=input('转入用户')money=input('转入金额')conn=MySQLdb.Connect(host='127.0.0.1',user='root',passwd='123456',port=3306,db='imooc')tr_money=TransferMoney(conn)try:tr_money.transfer(source_acctid,target_acctid,money)except Exception as e:print('出现问题：'+str(e))finally:conn.close()