python_MySQL之间的增删改查

代码片段一

连接并执行sql

#encoding:UTF-8import MySQLdbconn = MySQLdb.Connect(    host = '127.0.0.1',    port = 3306,    user = 'root',    passwd='123456',    db='imooc',    charset='utf8')cursor = conn.cursor()print connprint cursorsql = "select * from user"cursor.execute(sql) #执行

取数据

print cursor.rowcount#取数据#fetchone()获取一条数据#fetchany(3)获取多条#fetchall()#获取客户缓冲区的所有数据# rs = cursor.fetchone()# print rs## rs = cursor.fetchmany(2)# print rs## rs = cursor.fetchall()# print rs# rs = cursor.fetchall()# for row in rs:#     print "userid=%s,username=%s" % row

更新数据库

# sql_insert = "insert into user(userid,username) values(10,'name10')"# sql_update = "update user set username='name91' where userid=9"# sql_delete = "delete from user where userid<3"# cursor.execute(sql_insert)# cursor.execute(sql_update)# cursor.execute(sql_delete)# #执行完后提交# conn.commit()# #发生异常时回滚# try:#     sql_insert = "insert into user(userid,username) values(10,'name10')"#     sql_update = "update user set username='name91' where userid=9"#     sql_delete = "delete from user where userid<3"#     cursor.execute(sql_insert)#     cursor.execute(sql_update)#     cursor.execute(sql_delete)#     conn.commit()# except Exception as e:#     print e#     conn.rollback()cursor.close()conn.close()

代码片段2 银行实例

#coding:UTF-8import sysimport  MySQLdbclass TransferMoney(object):    def __init__(self,conn):        self.conn = conn    def tranfer(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()           raise e    def check_acct_available(self, acctid):        cursor = self.conn.cursor()        try:            sql = "select * from account where acctid=%s"%acctid            cursor.execute(sql)            rs = cursor.fetchall()            if len(rs)!=1:                raise Exception("账号%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("账号%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("账号%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("账号%s加款失败" % acctid)        finally:            cursor.close()if __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='123456',        db='imooc',        charset='utf8'    )    tr_money = TransferMoney(conn)    try:        tr_money.tranfer(source_acctid,target_acctid,money)    except Exception as e:        print "出现问题了" + str(e)    finally:        conn.close()