MySQL：选择除列之外仅具有唯一值的行

Question

Here is my situation: I have a table which duplicated values are valid (except by the ID field), and I'd like to retrieve only unique values.

For instance, if I have the registers:

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

I'd like to retrieve just 2 and 3 (ID 1 and 2 are "equal", and 3 has different TIME).

Here it is the table structure

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

Try:

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

Answer 2

You can apply the max() aggregate to the ID column and then GROUP BY the rest:

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

See SQL Fiddle with Demo

Result:

| 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

Try this:

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

or you can use 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;

This arbitrarily groups by differing values of SATELLITE_ID, ATT_TYPE_ID, TIME, ROLL, PITCH, and YAW. If you left out some of these fields, that only means there will potentially be less groups, having fewer reasons to differ from one another.