摘要： 为了方便进行实践，特将演示表和数据罗列如下：一、创建表create table t( bill_month varchar2(12) , area_code number, net_type varchar(2), local_fare number );二、插入数据insert into t values('200405',5761,'G', 7393344.04); insert into t values('200405',5761,'J', 5667089.85); insert into t values('20 阅读全文