新手求助：sql语句，从多个表中取出最新时间的记录，组成一个新表

mysql的实现：
insert into zongbiao(id, name ,vd,co2,wendu,time) select t1.id,t1.name,t1.vd,t2.co2,t2.wendu,t2.time from biao1 t1 join biao2 t2 on(t1.id=t2.id)
order by t2.time desc limit 1;

1.mysql和oracle通用版

create table loginfo(
id int primary key auto_increment, -- 主键
userId int not null, -- 用户id
loginTime timestamp -- 登录时间
);
insert into loginfo(userid, loginTime) values (1,'2015-01-12 14:36:20');
insert into loginfo(userid, loginTime) values (1,'2015-01-13 14:36:20');
insert into loginfo(userid, loginTime) values (1,'2015-01-13 14:46:20');
insert into loginfo(userid, loginTime) values (2,'2015-01-12 14:36:20');
insert into loginfo(userid, loginTime) values (2,'2015-01-13 14:36:20');
insert into loginfo(userid, loginTime) values (3,'2015-01-12 14:36:20');
insert into loginfo(userid, loginTime) values (4,'2015-01-12 14:36:20');
insert into loginfo(userid, loginTime) values (4,'2015-01-13 14:36:20');
insert into loginfo(userid, loginTime) values (4,'2015-01-14 14:36:20');
insert into loginfo(userid, loginTime) values (4,'2015-01-15 14:36:20');
insert into loginfo(userid, loginTime) values (5,'2015-01-12 14:36:20');
insert into loginfo(userid, loginTime) values (5,'2015-01-13 14:36:20');

-- 查询最后登录的时间
select * from loginfo t1 where loginTime = (select max(loginTime) from loginfo t2 where t1.userid=t2.userid);
-- 查询最早登录时间
select * from loginfo t1 where loginTime = (select min(loginTime) from loginfo t2 where t1.userid=t2.userid);

2.oracle去重思路
可以利用oracle的rowid进行去重

这样你就可以根据我的小例子来对机器id进行去重了。