MySQL：选择除列之外仅具有唯一值的行

Question

这是我的情况：我有一个表，其中重复的值是有效的（ID字段除外），并且我只想检索唯一的值。

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”，而3具有不同的TIME）。

这是表格结构

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    |                |
+--------------+--------------+------+-----+---------+----------------+

谢谢。

Answer 1

尝试：

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

Answer 2

您可以将max()集合应用于ID列，然后将其余部分应用于GROUP BY ：

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

参见带有演示的SQL Fiddle

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

尝试这个：

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

或者你可以使用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;

这可以根据SATELLITE_ID，ATT_TYPE_ID，TIME，ROLL，PITCH和YAW的不同值任意分组。 如果您忽略了其中一些字段，那仅意味着组的数量可能会减少，彼此之间差异的原因也就更少。