# Python DB API# 数据库连接对象 connection# 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# 数据库交互对象 cursor# 游标对象 用于执行查询和获取结果# execute(op[,args]) 执行一个数据库查询和命令# fetchone() 获取结果集的下一行# fetchmany(size) 获取结果集的下几行# fetchall() 获取结果集中剩下的所有行# rowcount 最近一次execute返回数据的行数或影响行数# close() 关闭游标对象# 安装# Python-MySQL connector# sourceforge.net/projects/mysql-python# 事务# 关闭自动commit conn.autocommit(False)# 否则每条sql作为事务单独提交# conn.commit()# conn.rollback()import MySQLdbconn = MySQLdb.Connect(    host = ‘127.0.0.1‘,    post = 3306,    user = ‘root‘,    passwd = ‘123456‘,    db = ‘imooc‘,    charset = ‘utf8‘    )def check_acct_available(acctid):    cursor = conn.cursor()    try:        sql = ‘select * from account where acctid=%s‘ % acctid        cursor.execute(sql)        cursor.rowcount        #cursor.fetchall()        #cursor.fetchmany(3)        rs = cursor.fetchone()        if len(rs) != 1:            raise Exception("账号%s不存在" % acctid)    finally:        cursor.close()def has_enough_money(acctid, money):    cursor = conn.cursor()    try:        sql = ‘select * from account where acctid=%s and money>%s‘ % (acctid, money)        cursor.execute(sql)        rs = cursor.fetchone()        if len(rs) != 1:            raise Exception("账号%s没有足够的钱" % acctid)    finally:        cursor.close()def reduce_money(acctid, money):    cursor = conn.cursor()    try:        sql = ‘update account set money=money-%s where acctid=%s‘ % (money, acctid)        cursor.execute(sql)        if cursor.rowcount != 1:            raise Exception("账号%s减款失败" % acctid)    finally:        cursor.close()def add_money(acctid, money):    cursor = conn.cursor()    try:        sql = ‘update account set money=money+%s where acctid=%s‘ % (money, acctid)        cursor.execute(sql)        if cursor.rowcount != 1:            raise Exception("账号%s加款失败" % acctid)    finally:        cursor.close()try:    check_acct_available(1)    has_enough_money(1, 100)    reduce_money(1, 100)    add_money(2, 100)    conn.commit()except Exception as e:    conn.rollback()finally:    conn.close()