在查詢返回值中填充間隙

Question

我有一個數據庫，其中包含以下列。

Id Date    Value 
1 12/01/2010 09:30 127.31 
1 12/01/2010 09:31 133.41 
1 12/01/2010 09:32 147.54 
1 12/01/2010 09:34 155.66 

本質上，我存儲對應於時間戳的值。但是，如果值爲0，我不存儲它（它是一個非常大的數據庫，並且0經常發生，所以我們決定不包含這些行以節省空間）。在上面的例子中，12/01/2010 09:33有一個0值，所以它沒有被存儲。然而，當用戶查詢數據庫時，他做了類似於

select * from table where Id = '1' and Date > to_date('12/01/2010', 'MM/DD/YYYY')` 

我需要填補空白並提供0值的時間戳。我怎樣才能做到這一點？

Answer 1

select 
    nvl(b.id,1) as id, 
    alldates.Date as Date, 
    nvl(b.value,0) as value 
from 
    (select level/1440 + to_date('12/01/2010', 'MM/DD/YYYY') as Date 
     from dual 
     connect by level < 1440 --one day 
    ) alldates 
    left join 
    (select * from table where Id = '1' and Date > to_date('12/01/2010', 'MM/DD/YYYY') b 
    on alldates.Date = b.Date 

修訂（響應評論）：

select 
    nvl(b.id,1) as id, 
    alldates.Date as Date, 
    nvl(b.value,0) as value, 
    nvl(b.value, lag(b.value) over (order by b.Date nulls last)) last_valid_value 
from 
    (select level/1440 + to_date('12/01/2010', 'MM/DD/YYYY') as Date 
     from dual 
     connect by level < 1440 --one day 
    ) alldates 
    left join 
    (select * from table where Id = '1' and Date > to_date('12/01/2010', 'MM/DD/YYYY') b 
    on alldates.Date = b.Date