pip install psycopg2

pymysql.Connect()参数说明
host(str):      MySQL服务器地址
port(int):      MySQL服务器端口号
user(str):      用户名
password(str):  密码
database(str):  数据库名称connection对象支持的方法
cursor()        使用该连接创建并返回游标
commit()        提交当前事务
rollback()      回滚当前事务
close()         关闭连接cursor对象支持的方法
execute(op)     执行一个数据库的查询命令
fetchone()      取得结果集的下一行
fetchmany(size) 获取结果集的下几行
fetchall()      获取结果集中的所有行
rowcount()      返回数据条数或影响行数
close()         关闭游标对象

-- ----------------------------
-- Table structure for account
-- ----------------------------
DROP TABLE IF EXISTS `account`;
CREATE TABLE `account`  (`acctid` varchar(50) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,`name` varchar(50) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,`money` decimal(50, 0) NULL DEFAULT NULL
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;-- ----------------------------
-- Records of account
-- ----------------------------
INSERT INTO `account` VALUES ('1', '张三', 50);
INSERT INTO `account` VALUES ('2', '李四', 150);

#   coding:utf8
import sysimport psycopg2 #PostgreSQL

class TransferMoney(object):def __init__(self, conn):self.conn = conndef check_acct_available(self, acctid):cursor = self.conn.cursor()try:sql = "select * from account where acctid='%s'" % acctidprint("check_acct_available:" + sql)cursor.execute(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)print("has_enough_money:" + sql)cursor.execute(sql)rs = cursor.fetchall()if len(rs) != 1:raise Exception("帐号%s没有足够的金额" % 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)print("reduce_money:" + sql)cursor.execute(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)print("add_money:" + sql)cursor.execute(sql)if cursor.rowcount != 1:raise Exception("帐号%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()print("transfer出现异常：" + str(e))raise edef main():source_acctid = sys.argv[1]print("转出帐号=" + source_acctid)target_acctid = sys.argv[2]print("转入帐号=" + target_acctid)money = sys.argv[3]print("金额=" + money)# 连接数据库 MySql#conn = pymysql.Connect(#    host='localhost',#    port=3306,#    user='root',#    passwd='root',#    db='OtkDb',#    charset='utf8')

    tr_money = TransferMoney(conn)try:tr_money.transfer(source_acctid, target_acctid, money)except Exception as e:print("main出现异常：" + str(e))finally:conn.close()if __name__ == '__main__':main()

PS H:\web\Python> & python h:\web\Python\01.MySql\db.py 1 2 50
转出帐号=1
转入帐号=2
金额=50
check_acct_available:select * from account where acctid='1'
check_acct_available:select * from account where acctid='2'
has_enough_money:select * from account where acctid='1' and money>50
reduce_money:update account set money=money-50 where acctid='1'
add_money:update account set money=money+50 where acctid='2'

PS H:\web\Python> & python h:\web\Python\01.MySql\db.py 1 2 50
转出帐号=1
转入帐号=2
金额=50
check_acct_available:select * from account where acctid='1'
check_acct_available:select * from account where acctid='2'
has_enough_money:select * from account where acctid='1' and money>50
transfer出现异常：帐号1没有足够的金额
main出现异常：帐号1没有足够的金额