如何从表限制中选择每列相同的值X结果

Question

我的桌子是：

id   uid  art_id  
---|-----|--------
1  | 10  |  11   |
2  | 11  |  23   | 
5  | 10  |  16   | 
3  | 10  |  13   | 
4  | 11  |  59   | 
6  | 11  |  36   |
7  | 11  |  55   | 
8  | 13  |  68   | 

我需要从表中从每个uid中选择两个结果art_id，但以行顺序最多选择两个。

更新：我有一个CCA 19m行的大型数据库，需要从每个用户中选择最后两篇文章（每个SQL请求限制用户200个）。按uid排序

结果将是：

id   uid  art_id  
---|-----|--------
1  | 10  |  11   |
5  | 10  |  16   | 
2  | 11  |  23   | 
4  | 11  |  59   | 
8  | 13  |  68   | 
3  | 10  |  13   |
6  | 11  |  36   | 
7  | 11  |  55   | 

Answer 1

SELECT MOD (ROW_NUM, 2) + TRUNC (ROW_NUM, 2) AS GROUPBY2,
     ROW_NUM,
     ID,
     UID,
     ART_ID
FROM (SELECT ROW_NUMBER ()
                OVER (PARTITION BY UID ORDER BY UID DESC)
                ROW_NUM,
             ID,
             UID,
             ART_ID
        FROM TABLE )
ORDER BY GROUPBY2