SQL在不同的列

Question

我有一个SQL表基于值滤波器重复行：

+-------------+-----------+---------+ 
|  ID  | position | user | 
+-------------+-----------+---------+ 
|  1  |  1  |  0 | 
|  2  |  2  |  0 | 
|  3  |  3  |  0 | 
|  4  |  4  |  0 | 
|  5  |  5  |  0 | 
|  6  |  6  |  0 | 
|  7  |  7  |  0 | 
|  8  |  7  |  1 | 
+-------------+-----------+---------+ 

我想基于位置栏和用户列的不同值来过滤重复的行，用于第一个查询我需要有以下结果：

+-------------+-----------+---------+ 
|  ID  | position | user | 
+-------------+-----------+---------+ 
|  1  |  1  |  0 | 
|  2  |  2  |  0 | 
|  3  |  3  |  0 | 
|  4  |  4  |  0 | 
|  5  |  5  |  0 | 
|  6  |  6  |  0 | 
|  8  |  7  |  1 | 
+-------------+-----------+---------+ 

对于第二个查询我需要以下条件：

+-------------+-----------+---------+ 
|  ID  | position | user | 
+-------------+-----------+---------+ 
|  1  |  1  |  0 | 
|  2  |  2  |  0 | 
|  3  |  3  |  0 | 
|  4  |  4  |  0 | 
|  5  |  5  |  0 | 
|  6  |  6  |  0 | 
|  7  |  7  |  0 | 
+-------------+-----------+---------+ 

我需要什么查询来实现这个目标？

感谢。

Answer 1

在没有进一步信息的情况下，下面的两个查询假定您想要通过在第二种情况下采用较大（最大）user值或第二种情况下较小（最小）user值来解决重复位置案件。

首先查询：

SELECT t1.* 
FROM yourTable t1 
INNER JOIN 
(
    SELECT position, MAX(user) AS max_user 
    FROM yourTable 
    GROUP BY position 
) t2 
    ON t1.position = t2.position AND 
     t1.user  = t2.max_user 

第二个查询：

SELECT t1.* 
FROM yourTable t1 
INNER JOIN 
(
    SELECT position, MIN(user) AS min_user 
    FROM yourTable 
    GROUP BY position 
) t2 
    ON t1.position = t2.position AND 
     t1.user  = t2.min_user