mysql 查询表中 字段没有重复值的数据

[dxlqiu]

比如说 有个表
id title time
1 a 20120304
2 a 20121314
3 b 20121314
4 c 20121111
5 d 20121221
6 c 20121111

第一种想要的结果：
想查出title没有重复的数据 有没有办法
想要结果 为
id title time
3 b 20121314
5 d 20121221

第二种想要的结果
第一种多加个条件，如果title相同 但是time也相同 那也显示出这条数据(仅一条)
id title time
3 b 20121314
4 c 20121111
5 d 20121221

大家有没有好的办法

[小小小小周]

root@localhost : test 04:59:19>select * from tes;
+------+-------+----------+
| id   | title | time     |
+------+-------+----------+
|    1 | a     | 20120304 |
|    2 | a     | 20121314 |
|    3 | b     | 20121314 |
|    4 | c     | 20121111 |
|    5 | d     | 20121221 |
|    6 | c     | 20121111 |
+------+-------+----------+
6 rows in set (0.00 sec)

root@localhost : test 04:59:22>select a.* from tes a,(select title,count(*) from tes group by title having count(*)=1) b where a.title=b.title;
+------+-------+----------+
| id   | title | time     |
+------+-------+----------+
|    3 | b     | 20121314 |
|    5 | d     | 20121221 |
+------+-------+----------+
2 rows in set (0.00 sec)

root@localhost : test 04:59:47>select id,title,time from tes group by title,time;
+------+-------+----------+
| id   | title | time     |
+------+-------+----------+
|    1 | a     | 20120304 |
|    2 | a     | 20121314 |
|    3 | b     | 20121314 |
|    4 | c     | 20121111 |
|    5 | d     | 20121221 |
+------+-------+----------+
5 rows in set (0.00 sec)

[dxlqiu]

有么有帮忙的呀。。。。。

[foolbirdflyfirst]

这类问题似乎此版很多，你不妨搜索下

mysql> select * from tb;
+----+-------+----------+
| id | title | time     |
+----+-------+----------+
|  1 | a     | 20120304 |
|  2 | a     | 20121314 |
|  3 | b     | 20121314 |
|  4 | c     | 20121111 |
|  5 | d     | 20121221 |
|  6 | c     | 20121111 |
+----+-------+----------+
6 rows in set (0.00 sec)

mysql> select * from tb a where not exists(select id from tb b where b.title=a.title and b.id<>a.id);
+----+-------+----------+
| id | title | time     |
+----+-------+----------+
|  3 | b     | 20121314 |
|  5 | d     | 20121221 |
+----+-------+----------+
2 rows in set (0.00 sec)

mysql> select * from tb a where not exists(select id from tb b where b.title=a.title and b.id<>a.id and b.time<>a.time) group by a.title;
+----+-------+----------+
| id | title | time     |
+----+-------+----------+
|  3 | b     | 20121314 |
|  4 | c     | 20121111 |
|  5 | d     | 20121221 |
+----+-------+----------+
3 rows in set (0.00 sec)

[dxlqiu]

谢谢楼上的两位。。 本来我是用字段not in 来查询的 但是 发现速度太慢了 2W多条数据 就花了1秒多了
貌似用not exists 加个select 的话 速度是不是很会很慢呀。。

[wwwwb]

1
select * from tt a where not exists(select 1 from tt where a.title=title and a.id<>id)
2



select * from tt a where exists(select 1 from tt where a.title=title and a.time=time and a.id<id)
union
select * from tt a where not exists(select 1 from tt where ((a.title=title and a.id<>id)
or
(a.title=title and a.time=time and a.id<id)))

[dxlqiu]

Ok 谢谢 各位 大侠们
not exists效率确实挺高的
比not in好多了。好了 结贴了