获得最后一次时间的记录

CREATE TABLE `wsz2` (
  `id` int(11) NOT NULL,
  `name` varchar(5) NOT NULL,
  `time` datetime NOT NULL,
  PRIMARY KEY (`id`),
  KEY `name` (`name`,`time`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

#
# 导出表中的数据 `wsz2`
#

INSERT INTO `wsz2` (`id`, `name`, `time`) VALUES (1, 'a', '2011-05-01 10:00:00'),
(2, 'a', '2011-05-02 10:00:00'),
(3, 'b', '2011-05-02 12:00:00'),
(4, 'b', '2011-05-03 12:00:00');


--------------
取出来的结果就是这二条
(2, 'a', '2011-05-02 10:00:00'),

(4, 'b', '2011-05-03 12:00:00');

select * from `wsz2` a where not exists(select 1 from `wsz2` where a.`name`=`name`
and a.`time`<`time`)

参考下贴中的多种方法

http://topic.csdn.net/u/20091231/16/2f268740-391e-40f2-a15e-f243b2c925ab.html
[征集]分组取最大N条记录方法征集，及散分....

其中的一种解法。
SQL code

mysql> select * from wsz2;
+----+------+---------------------+
| id | name | time                |
+----+------+---------------------+
|  1 | a    | 2011-05-01 10:00:00 |
|  2 | a    | 2011-05-02 10:00:00 |
|  3 | b    | 2011-05-02 12:00:00 |
|  4 | b    | 2011-05-03 12:00:00 |
+----+------+---------------------+
4 rows in set (0.00 sec)

mysql> select * from (select * from wsz2 order by time desc) t group by name;
+----+------+---------------------+
| id | name | time                |
+----+------+---------------------+
|  2 | a    | 2011-05-02 10:00:00 |
|  4 | b    | 2011-05-03 12:00:00 |
+----+------+---------------------+
2 rows in set (0.00 sec)

mysql>

不好意思，其实我还有个条件，本想在这个语句上加，但加上不行。补充一下：
wsz2.name=table.name and table.zone='xxx'

---------------
我是这么加的：

select wsz2.*,table.* from (select * from wsz2 order by time desc) t,table where wsz2.name=table.name and table.zone='xxx' group by wsz2.name;

(不要高估你的汉语表达能力或者我的汉语理解能力)
  建议你列出你的表结构，并提供测试数据以及基于这些测试数据的所对应正确结果。
  参考一下这个贴子的提问方式http://topic.csdn.net/u/20091130/20/8343ee6a-417c-4c2d-9415-fa46604a00cf.html
   
  1. 你的 create table xxx .. 语句
  2. 你的 insert into xxx ... 语句
  3. 结果是什么样，（并给以简单的算法描述）
  4. 你用的数据库名称和版本(经常有人在MS SQL server版问 MySQL)
   
  这样想帮你的人可以直接搭建和你相同的环境，并在给出方案前进行测试，避免文字描述理解上的误差。

 

SQL code

select t.*,table.* 
from (select * from wsz2 order by time desc) t Inner Join
table on t.name=table.name
where table.zone='xxx' 
group by t.name

CREATE TABLE `wsz2` (
  `id` int(11) NOT NULL,
  `name` varchar(5) NOT NULL,
  `time` datetime NOT NULL,
  PRIMARY KEY (`id`),
  KEY `name` (`name`,`time`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

#
# 导出表中的数据 `wsz2`
#

INSERT INTO `wsz2` (`id`, `name`, `time`) VALUES (1, 'a', '2011-05-01 10:00:00'),
(2, 'a', '2011-05-02 10:00:00'),
(3, 'b', '2011-05-02 12:00:00'),
(4, 'b', '2011-05-03 12:00:00');
(5, 'c', '2011-05-03 12:00:00');




CREATE TABLE `table` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(5) NOT NULL,
  `zone` varchar(10) NOT NULL,
  PRIMARY KEY (`id`),
  KEY `name` (`name`,`zone`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=latin1 AUTO_INCREMENT=4 ;

#
# 导出表中的数据 `table`
#

INSERT INTO `table` (`id`, `name`, `zone`) VALUES (1, 'a', '音乐组'),
(2, 'b', '音乐组'),
(3, 'c', '数学组');
------------------------------------

--------------
取出来wsz2表的最后一个时间的记录，并且table.zone=音乐组 的结果就是这二条. 
二表关联条件是：wsz2.name=table.name

(2, 'a', '2011-05-02 10:00:00'),

(4, 'b', '2011-05-03 12:00:00');

SQL code

-- 假设id是自增字段，假设table表内name不重复
SELECT max(w.id), w.name, max(w.time)
  FROM wsz2 w, table t
 WHERE w.name = t.name
   AND t.zone = 'xxx'
 GROUP BY w.name

-- 假设id是自增字段，假设table表内name可能重复
SELECT max(w.id), w.name, max(w.time)
  FROM wsz2 w
 WHERE EXISTS (SELECT 1 FROM table t WHERE w.name = t.name AND t.zone = 'xxx')
 GROUP BY w.name

TO ALL，
一般，id就是自增字段。time晚的，id必然大，因此没必要自联，直接max即可。

+1

SQL code

mysql> select * from (select wsz2.* from wsz2,`table` where wsz2.name=`table`.na
me and `table`.zone='音乐组' order by wsz2.time desc) t group by name;
+----+------+---------------------+
| id | name | time                |
+----+------+---------------------+
|  2 | a    | 2011-05-02 10:00:00 |
|  4 | b    | 2011-05-03 12:00:00 |
+----+------+---------------------+
2 rows in set (0.05 sec)

mysql>

SQL code

SELECT max(w.id), w.name, max(w.time)
  FROM wsz2 w, table t
 WHERE w.name = t.name
   AND t.zone = '音乐组'
 GROUP BY w.name

直接这样就可以了吧