介绍：本文是关于数据库的简单操作，实现转账（只是修改数据库中用户的账户金额）的功能
模块介绍：首先是入口主函数 主函数中实现转账方法 以及异常的处理：
if __name__ == "__main__":
source_acctid = sys.argv[1] #获取命令行第一个参数
target_acctid = sys.argv[2]
money = sys.argv[3] #连接数据库
conn = MySQLdb.Connect(host = '127.0.0.1',user = 'root',passwd = 'root',port = 3306,db = 'account')
tr_money = TransferMoney(conn) try:
tr_money.transfer(source_acctid,target_acctid,money) #转账操作
except Exception as e:
print "出现问题" + str(e)
finally:
conn.close()#关闭数据库连接
然后是实现转账的类，以及类中实现的方法 1.判断用户账户中的金额 2.判断账户是否存在 3.扣除账户金额 4.增加账户金额
class TransferMoney(object):
def __init__(self, conn):
self.conn = conn
def check_acct_available(self, acctid):
cursor = self.conn.cursor()
try:
sql = "select * from account_user where accountid=%s"%acctid
cursor.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()
def has_enough_money(self, acctid, money):
cursor = self.conn.cursor()
try:
sql = "select * from account_user where accountid=%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()
def reduce_money(self, acctid, money):
cursor = self.conn.cursor()
try:
sql = "update account_user set money=money-%s where accountid=%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_user set money=money+%s where accountid=%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) #检查转账账户是否可用
self.check_acct_available(target_acctid)
self.has_enough_money(source_acctid,money) #检查账户钱是否足够
self.reduce_money(source_acctid,money) #扣除钱
self.add_money(target_acctid,money) #转账加钱
self.conn.commit()
except Exception as e:
self.conn.rollback() #如果有步骤出错 则事务回滚
raise e # raise的作用是将异常抛出到上一级处理