Question

In some of the hours I insert data to DB with timestamp. I want to have hourly view with rows without records filled with last record data :

Table

DateTime Value  
12     4  
15     6  

Desired Result

DateTime Value  
12       4  
13       4  
14       4  
15       6  
16       6  

It should be possible, but I can’t think about any effective way..

How can this be done?

Answer 1

OK having misread the question once and provided an answer that leaves the gaps efficiently; in order to get the last value out in sql you will need to loop the data which is less efficient.

Create Table tblMyValues (MyHours int, MyValue int)
Insert into tblMyValues select 12, 4
Insert into tblMyValues select 15, 6
Insert into tblMyValues select 15, 6


Create Table tblResult (MyHour int, ReportValue Int)

Declare @i Int = 0, @LastValue Int
While @i <= 24
Begin

select @i = @i + 1
Select @LastValue = coalesce(MyValue, @LastValue)
From tblMyValues
Where MyHours = @i

    insert into tblResult 
    Select @i, @LastValue

End

select * from tblResult
drop table tblMyValues
drop table tblResult

This returns

MyHour      ReportValue
----------- -----------
1           NULL
2           NULL
3           NULL
4           NULL
5           NULL
6           NULL
7           NULL
8           NULL
9           NULL
10          NULL
11          NULL
12          4
13          4
14          4
15          6
16          6
17          6
18          6
19          6
20          6
21          6
22          6
23          6
24          6