How do perform a "customized" running total in SQL Server? - tsql

Question

I have temp table that I've populated with a running total. I used SQL Server windowing functions. The data in my temp table is in the following format:
|Day | Sku Nbr | CMQTY |
| 1 | f45 | 0 |
| 2 | f45 | 2 |
| 3 | f45 | 0 |
| 4 | f45 | 7 |
| 5 | f45 | 0 |
| 6 | f45 | 0 |
| 7 | f45 | 0 |
| 8 | f45 | 13 |
| 9 | f45 | 15 |
| 10 | f45 | 21 |
I would like to manipulate the data so that it displays like this:
|Day| Sku Nbr | CMQTY |
| 1 | f45 | 0 |
| 2 | f45 | 2 |
| 3 | f45 | 2 |
| 4 | f45 | 7 |
| 5 | f45 | 7 |
| 6 | f45 | 7 |
| 7 | f45 | 7 |
| 8 | f45 | 13 |
| 9 | f45 | 15 |
| 10 | f45 | 21 |
I've tried using a lag function but there are issues when I have multiple days, in a row, with a 0 CMQTY. I've also tried using CASE WHEN logic but am failing.

Answer 1

You can use row_number as below
;with cte as (
select *, sm = sum(case when cmqty>0 then 1 else 0 end) over (order by [day]) from #yoursum
)
select *, sum(cmqty) over(partition by sm order by [day]) from cte
Your table structure
create table #yoursum ([day] int, sku_nbr varchar(10), CMQTY int)
insert into #yoursum
([Day] , Sku_Nbr , CMQTY ) values
( 1 ,'f45', 0 )
,( 2 ,'f45', 2 )
,( 3 ,'f45', 0 )
,( 4 ,'f45', 7 )
,( 5 ,'f45', 0 )
,( 6 ,'f45', 0 )
,( 7 ,'f45', 0 )
,( 8 ,'f45', 13 )
,( 9 ,'f45', 15 )
,( 10 ,'f45', 21 )

Answer 2

For fun, another approach. First for some sample data:
IF OBJECT_ID('tempdb..#t1') IS NOT NULL DROP TABLE #t1;
CREATE TABLE #t1
(
[day] int NOT NULL,
[Sku Nbr] varchar(5) NOT NULL,
CMQTY int NOT NULL,
CONSTRAINT pk_t1 PRIMARY KEY CLUSTERED([day] ASC)
);
INSERT #t1 VALUES
(1 , 'f45', 0),
(2 , 'f45', 2),
(3 , 'f45', 0),
(4 , 'f45', 7),
(5 , 'f45', 0),
(6 , 'f45', 0),
(7 , 'f45', 0),
(8 , 'f45', 13),
(9 , 'f45', 15),
(10, 'f45', 21);
And the solution:
DECLARE #RunningTotal int = 0;
UPDATE #t1
SET #RunningTotal = CMQTY = IIF(CMQTY = 0, #RunningTotal, CMQTY)
FROM #t1 WITH (TABLOCKX)
OPTION (MAXDOP 1);
Results:
day Sku Nbr CMQTY
---- ------- ------
1 f45 0
2 f45 2
3 f45 2
4 f45 7
5 f45 7
6 f45 7
7 f45 7
8 f45 13
9 f45 15
10 f45 21
This approach is referred to the local updateable variable or Quirky Update. You can read more about it here: http://www.sqlservercentral.com/articles/T-SQL/68467/