import pymysql

class TransferMoney(object):
    def __init__(self,conn):
        self.conn = conn
        self.cur = conn.cursor()


    def transfer(self,source_accid,target_accid,money):
        '''
        :param source_accid:原帳號id
        :param target_accid: 目標帳號id
        :return: bool
        '''
 

        #判斷帳號是否存在
        self.check_account_avaiable(source_accid)
        self.check_account_avaiable(target_accid)
        #判斷原帳號是否有足夠的錢
        self.has_enough_money(source_accid,money)

        try:
            #扣錢
            self.reduce_money(source_accid,money)
            #加錢
            self.add_money(target_accid,money)
            self.conn.commit()
        except
 
 Exception as e:
            #撤銷對資料庫的操作，回滾
            self.conn.rollback()
        else:
            print('轉賬成功')



    def check_account_avaiable(self,accid):
        '''目標帳號是否存在'''
        select_sqli = 'select * from bankdata where id=%s' %accid
        res = self.cur.execute(select_sqli)
        if
 
 res == 1:
            return True
        else:
            raise Exception('賬戶%s不存在' %accid)

    def has_enough_money(self,accid,money):
        '''是否有足夠的錢'''
        select_sqli = 'select * from bankdata where id=%s' %accid
        self.cur.execute(select_sqli)
        res = self.cur.fetchone()[1]
        if res >= money:
            return True
        else:
            raise Exception('賬戶%s餘額不足' %accid)

    def reduce_money(self,accid,money):
        '''對原賬戶的錢進行扣除'''
        try:
            update_sqli = 'update bankdata set money=money-%d where id="%s";' %(money,accid)
            self.cur.execute(update_sqli)
        except Exception as e:
            print('error:',e)

    def add_money(self,accid,money):
        '''對目標賬戶的錢數進行新增'''
        try:
            updata_sqli = 'update bankdata set money=money+%d where id="%s";' %(money,accid)
            self.cur.execute(updata_sqli)
        except Exception as e:
            print('error:',e)

    def __del__(self):
        '''當刪除物件時自動執行關閉遊標的操作'''
        self.cur.close()

if __name__=='__main__':
    conn = pymysql.connect(host='localhost',user='root',password='westos',
                           charset='utf8',db='redhat')

    tran = TransferMoney(conn)
    tran.transfer('001','002',1000)

轉賬前的賬戶資訊：

轉賬後的賬戶資訊：