问个数据库查询的问题
例如表结构如下：
key time value
1 100 5
1 101 7
1 102 9
2 100 6
2 101 10
key为关键字
现在要查询时间值最大的各个关键字所对应的记录
例如上面对于关键字1，时间值最大为102，对于关键字2，时间值最大为101，那么查询结果应为：
1 102 9
2 101 10
请问查询语句该怎么写？
[解决办法]
create table b1 (`key` int not null,`time` int not null,`value` int not null) engine=myisam default charset=utf8;
insert into b1 values
(1, 100, 5),
(1, 101, 7),
(1, 102, 9),
(2, 100, 6),
(2, 101, 10);
select * from (select * from b1 order by `time` desc ) T group by `key`;
drop table b1;
=========
query result(2 records)
keytimevalue
1 102 9
2 101 10
[解决办法]
戏法人人会变，各有巧妙不同：
SELECT t1 . *
FROM b1 t1, (
SELECT `key` , max( `time` ) AS maxtime
FROM b1
GROUP BY `key`
)t2
WHERE t1.`key` = t2.`key`
AND t1.time = t2.maxtime
