甲骨文 - 按類別分組，日期範圍

Question

我有一個問題。我想寫Oracle查詢，其基於從圖像數據

將創建結果數據庫：

START_DATE   |END_DATE   |COLOR 
-------------------|-------------------|------ 
2017-05-25 15:39:39|2017-05-25 15:41:06|GREEN 
2017-05-25 15:41:06|2017-05-25 15:53:27|ORANGE 
2017-05-25 15:53:27|2017-05-25 15:57:16|GREEN 
2017-05-25 15:57:16|2017-05-25 15:59:24|YELLOW 

等您正在嘗試...

Answer 1

找到相鄰的值。一種方法使用行號的差異：

select min(start_date) as start_date, max(start_date) as end_date, color 
from (select t.*, 
      row_number() over (order by start_date) as seqnum, 
      row_number() over (partition by color order by start_date) as seqnum_c 
     from t 
group by (seqnum - seqnum_c), color; 

解釋爲什麼行號差異起作用有點具有挑戰性。我鼓勵你運行子查詢並盯着數字。你應該能夠明白爲什麼相鄰顏色值的差異是恆定的。