Question

这是我的情况：我有一个表，其中重复的值有效（ID字段除外），我只想检索唯一值。

例如，如果我有寄存器：

+----+--------------+-------------+------+------+-------+-----+
| ID | SATELLITE_ID | ATT_TYPE_ID | TIME | ROLL | PITCH | YAW |
+----+--------------+-------------+------+------+-------+-----+
|  1 |            1 |           1 | 2012 |  1.0 |   2.0 | 1.3 |
+----+--------------+-------------+------+------+-------+-----+
|  2 |            1 |           1 | 2012 |  1.0 |   2.0 | 1.3 |
+----+--------------+-------------+------+------+-------+-----+
|  3 |            1 |           1 | 2011 |  1.0 |   2.0 | 1.3 |
+----+--------------+-------------+------+------+-------+-----+

我只想检索2和3（ID 1和2是“相等”，3有不同的TIME）。

这是表结构

mysql> describe attitude;
+--------------+--------------+------+-----+---------+----------------+
| Field        | Type         | Null | Key | Default | Extra          |
+--------------+--------------+------+-----+---------+----------------+
| ID           | int(11)      | NO   | PRI | NULL    | auto_increment |
| SATELLITE_ID | int(11)      | NO   |     | NULL    |                |
| ATT_TYPE_ID  | int(11)      | NO   |     | NULL    |                |
| TIME         | varchar(4)   | NO   |     | NULL    |                |
| ROLL         | double       | NO   |     | NULL    |                |
| PITCH        | double       | NO   |     | NULL    |                |
| YAW          | double       | NO   |     | NULL    |                |
+--------------+--------------+------+-----+---------+----------------+

THX。

Answer 1

尝试：

SELECT DISTINCT SATELLITE_ID, ATT_TYPE_ID, TIME, ROLL, PITCH, YAW
FROM ATTITUDE

Answer 2

您可以将max()汇总应用于ID列，然后GROUP BY应用其余部分：

select max(id) id, SATELLITE_ID, ATT_TYPE_ID, TIME, Roll, Pitch, yaw
from attitude
group by SATELLITE_ID, ATT_TYPE_ID, TIME, Roll, Pitch, yaw
order by id

请参阅SQL Fiddle with Demo

结果：

| ID | SATELLITE_ID | ATT_TYPE_ID | TIME | ROLL | PITCH | YAW |
---------------------------------------------------------------
|  2 |            1 |           1 | 2012 |    1 |     2 |   1 |
|  3 |            1 |           1 | 2011 |    1 |     2 |   1 |

Answer 3

试试这个：

select SATELLITE_ID, ATT_TYPE_ID, TIME, ROLL, PITCH, YAW 
from ATTITUDE
group by SATELLITE_ID, ATT_TYPE_ID, TIME, ROLL, PITCH, YAW

或者您可以使用distinct

select distinct SATELLITE_ID, ATT_TYPE_ID, TIME, ROLL, PITCH, YAW 
from ATTITUDE

Answer 4

select max(ID) from attitude
  group by SATELLITE_ID, ATT_TYPE_ID, TIME, ROLL, PITCH, YAW;

通过SATELLITE_ID，ATT_TYPE_ID，TIME，ROLL，PITCH和YAW的不同值任意分组。如果你遗漏了其中的一些字段，那只意味着可能会有更少的群体，彼此之间的差异较小。

MySQL：选择除列之外只有唯一值的行

4 个答案: