python操作mysql--银行转账实例

#coding:UTF8
#思路是：1 判断两个账户是否合法存在
#     2 判断原账户钱是否够
#     3 转出账户 减款
#     4 转入账户 加款
import sys
import MySQLdb

class Zhuanzhang(object):

def __init__(self, conn):
self.conn = conn

def check_acct_available(self, acctid):
cursor = self.conn.cursor()
try:
sql = "select * from account where acctid=%s" % acctid
cursor.execute(sql)
print "check_acct_available:"+sql
rs = cursor.fetchall()
if len(rs) !=1:
raise Exception("帐号%s不存在"% acctid)
finally:
cursor.close()

def has_enough_money(self, acctid, money):
cursor = self.conn.cursor()
try:
sql = "select * from account 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("帐号%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 set money=money-%s where acctid=%s" % (money,acctid)
cursor.execute(sql)
print "reduce_money:"+sql
if cursor.rowcount!=1:
raise Exception("帐号%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 "reduce_money:"+sql
if cursor.rowcount!=1:
raise Exception("帐号%s加款失败"% acctid)
finally:
cursor.close()

def zhuanzhang(self,zhuanchu_acctid,zhuanru_acctid,money):
try:
self.check_acct_available(zhuanchu_acctid)
self.check_acct_available(zhuanru_acctid)
self.has_enough_money(zhuanchu_acctid,money)
self.reduce_money(zhuanchu_acctid,money)
self.add_money(zhuanru_acctid,money)
self.conn.commit()
except Exception as e:
self.conn.rollback()
raise e

if __name__ == "__main__":
zhuanchu_acctid =sys.argv[1]
zhuanru_acctid = sys.argv[2]
money = sys.argv[3]

conn = MySQLdb.Connect(host='127.0.0.1',user='root',passwd='',port=3306,db='imooc')
zhuanzhang = Zhuanzhang(conn)
try:
zhuanzhang.zhuanzhang(zhuanchu_acctid,zhuanru_acctid,money)
except Exception as e:
print "出现问题:"+str(e)
finally:
conn.close()