SQL從子查詢中選擇

Question

我在從子查詢中選擇具有此小演示數據的問題，例如：

ID          CLASS_ID               PROP          STATUS        ROW     SELECTED    STEP
12345679    1312            0         21           3       07-FEB-14    1
12345679    1312            0         21           1       26-FEB-14    -1

我想獲取所有信息（每列），下面的sql正常運行

SELECT ID,CLASS_ID,min(SELECTED) FROM ( SELECT... ) GROUP BY ID,CLASS_ID

ID          CLASS_ID             SELECTED   
12345679    1312                07-FEB-14   

但是，如果我想要其他列，則必須將它們添加到group語句中，否則我將獲得“ not a group statement”，從而使它過時，有什么想法嗎？

Answer 1

您要使用分析功能row_number() ：

select ID, CLASS_ID, PROP, STATUS, ROW, SELECTED  
from (select s.*, row_number() over (partition by id, class_id
                                     order by selected desc) as seqnum
      from (<subquery>) s
     ) s
where seqnum = 1;

Answer 2

您想要基於組ID和所有其他列的class_id獲得最少的selected列，則可以MIN() over partitioned by函數MIN() over partitioned by使用MIN() over partitioned by -

SELECT ID,
       CLASS_ID,
       min(SELECTED) over (partition by ID,CLASS_ID order by 1) , 
       col1 ...
FROM ( SELECT... )