Python实现完整的事务操作示例

#coding=utf-8import sysimport MySQLdbclass TransferMoney(object):  def __init__(self,conn):    self.conn = conn  #检查账户是否合法  def check_acct_avaiable(self,acctid):    cursor = self.conn.cursor()    try:      sql = "select * from account where acctid=%s" % acctid      cursor.execute(sql)      print "check account:" + sql      rs = cursor.fetchall()      if len(rs) != 1:        raise Exception("account %s illega" % acctid)    finally:      cursor.close()  #检查是否有足够的钱  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("account %s not enough money" % acctid)    finally:      cursor.close()  #账户减钱  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("reduce money fail %s" % acctid)    finally:      cursor.close()  #账户加钱  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("add money fail %s" % acctid)    finally:      cursor.close()  #主执行语句  def transfer(self,source_acctid,target_acctid,money):    try:      self.check_acct_avaiable(source_acctid)      self.check_acct_avaiable(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[1]  target_acctid = sys.argv[2]  money = sys.argv[3]  conn = MySQLdb.Connect(host = '127.0.0.1',port=3306,user='root',passwd='',db='test',charset='utf8')  tr_money = TransferMoney(conn)  try:    tr_money.transfer(source_acctid,target_acctid,money)  except Exception as e:    print "Happen:" + str(e)  finally:    conn.close()