我有一个包含如下列的数据库。
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
本质上,我存储与时间戳对应的值。但是,如果值为 0,我不存储它(它是一个非常大的数据库,并且 0 经常出现,所以我们决定不包括这些行以节省空间)。在上面的例子中,
12/01/2010 09:33
有一个 0 值所以它不存储。但是,当用户查询数据库时,他会执行类似的操作select * from table where Id = '1' and Date > to_date('12/01/2010', 'MM/DD/YYYY')`
我需要填补空白并使用 0 值提及时间戳。我怎样才能做到这一点?
最佳答案
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
更新 (回复评论):
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
关于sql - 填补查询返回值的空白,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/8253612/