归类 : Python
文集 : Python杂记

Python3.x 使用 pymysql 操作数据库

前言

    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
    passwd(str):    密码
    db(str):        数据库名称
    charset(str):   连接编码
    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

MySQL

创建一个交易表

    DROP TABLE IF EXISTS `trade`;
    CREATE TABLE `trade` (
        `id` int(4) unsigned NOT NULL AUTO_INCREMENT,
        `name` varchar(6) NOT NULL COMMENT '用户真实姓名',
        `account` varchar(11) NOT NULL COMMENT '银行储蓄账号',
        `saving` decimal(8,2) unsigned NOT NULL DEFAULT '0.00' COMMENT '账户储蓄金额',
        `expend` decimal(8,2) unsigned NOT NULL DEFAULT '0.00' COMMENT '账户支出总计',
        `income` decimal(8,2) unsigned NOT NULL DEFAULT '0.00' COMMENT '账户收入总计',
        PRIMARY KEY (`id`),
        UNIQUE KEY `name_UNIQUE` (`name`)
    ) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8;
    INSERT INTO `trade` VALUES (1,'乔布斯','18012345678',0.00,0.00,0.00);

增删改查和事务处理

连接数据库

    import pymysql.cursors
    connect = pymysql.Connect(
            host='localhost',
            port=3310,
            user='woider',
            passwd='3243',
            db='python',
            charset='utf8'
    )

获取游标

    cursor = connect.cursor()

插入数据

    sql = "INSERT INTO trade (name, account, saving) VALUES ( '%s', '%s', %.2f )"
    data = ('雷军', '13512345678', 10000)
    cursor.execute(sql % data)
    connect.commit()
    print('成功插入', cursor.rowcount, '条数据')

修改数据

    sql = "UPDATE trade SET saving = %.2f WHERE account = '%s' "
    data = (8888, '13512345678')
    cursor.execute(sql % data)
    connect.commit()
    print('成功修改', cursor.rowcount, '条数据')

查询数据

    sql = "SELECT name,saving FROM trade WHERE account = '%s' "
    data = ('13512345678',)
    cursor.execute(sql % data)
    for row in cursor.fetchall():
            print("Name:%s\tSaving:%.2f" % row)
    print('共查找出', cursor.rowcount, '条数据')

删除数据

    sql = "DELETE FROM trade WHERE account = '%s' LIMIT %d"
    data = ('13512345678', 1)
    cursor.execute(sql % data)
    connect.commit()
    print('成功删除', cursor.rowcount, '条数据')

事务处理

    sql_1 = "UPDATE trade SET saving = saving + 1000 WHERE account = '18012345678' "
    sql_2 = "UPDATE trade SET expend = expend + 1000 WHERE account = '18012345678' "
    sql_3 = "UPDATE trade SET income = income + 2000 WHERE account = '18012345678' "
    try:
            cursor.execute(sql_1)  # 储蓄增加1000
            cursor.execute(sql_2)  # 支出增加1000
            cursor.execute(sql_3)  # 收入增加2000
    except Exception as e:
            connect.rollback()  # 事务回滚
            print('事务处理失败', e)
    else:
            connect.commit()  # 事务提交
            print('事务处理成功', cursor.rowcount)

关闭连接

    cursor.close()
    connect.close()

以上