select user_id,name,max(time)
from a
group by user_id,name

------解决方案--------------------
SQL code

create table a
(user_id number(8),
name varchar2(20),
time date);

insert into a values(33,'www',to_date('2010-07-08','yyyy-mm-dd'));
insert into a values(33,'www',to_date('2010-06-07','yyyy-mm-dd'));
insert into a values(33,'www',to_date('2010-05-06','yyyy-mm-dd'));
insert into a values(44,'www',to_date('2010-05-07','yyyy-mm-dd'));
insert into a values(44,'www',to_date('2010-06-25','yyyy-mm-dd'));


create table b
(user_id number(8),
name varchar2(20),
time date);

insert into b (
select  user_id,name,max(time)
from a
group by user_id,name);

------解决方案--------------------
探讨

很详细  
SQL code

create table a
(user_id number(8),
name varchar2(20),
time date);

insert into a values(33,'www',to_date('2010-07-08','yyyy-mm-dd'));
insert into a values(33,'www',to_date('2010-06-07','yy……


------解决方案--------------------
select user_id name ,max(time) from A group by user_id

------解决方案--------------------
select user_id ,name,max(time) from a group by user_id;