Transact-SQL - number rows until condition met - sql-server

Question

I'm trying to generate the numbers in the "x" column considering the values in field "eq", in a way that it should assign a number for every record until it meets the value "1", and the next row should reset and start counting again. I've tried with row_number, but the problem is that I only have ones and zeros in the column I need to evaluate, and the cases I've seen using row_number were using growing values in a column. Also tried with rank, but I haven't managed to make it work.
nInd Fecha Tipo #Inicio #contador_I #Final #contador_F eq x
1 18/03/2002 I 18/03/2002 1 null null 0 1
2 20/07/2002 F 18/03/2002 1 20/07/2002 1 1 2
3 19/08/2002 I 19/08/2002 2 20/07/2002 1 0 1
4 21/12/2002 F 19/08/2002 2 21/12/2002 2 1 2
5 17/03/2003 I 17/03/2003 3 21/12/2002 2 0 1
6 01/04/2003 I 17/03/2003 4 21/12/2002 2 0 2
7 07/04/2003 I 17/03/2003 5 21/12/2002 2 0 3
8 02/06/2003 F 17/03/2003 5 02/06/2003 3 0 4
9 31/07/2003 F 17/03/2003 5 31/07/2003 4 0 5
10 31/08/2003 F 17/03/2003 5 31/08/2003 5 1 6
11 01/09/2005 I 01/09/2005 6 31/08/2003 5 0 1
12 05/09/2005 I 01/09/2005 7 31/08/2003 5 0 2
13 31/12/2005 F 01/09/2005 7 31/12/2005 6 0 3
14 14/01/2006 F 01/09/2005 7 14/01/2006 7 1 4

Answer 1

There is another solution available:
select
nind, eq, row_number() over (partition by s order by s)
from (
select
nind, eq, coalesce((
select sum(eq) +1 from mytable pre where pre.nInd < mytable.nInd)
,1) s --this is the sum of eq!
from mytable) g
The inner subquery creates groups sequentially for each occurrence of 1 in eq. Then we can use row_number() over partition to get our counter.
Here is an example using Sql Server

Answer 2

I have two answers here. One is based off of the ROW_NUMBER() and the other is based off of what appears to be your index (nInd). I wasn't sure if there would be a gap in your index so I made the ROW_NUMBER() as well.
My table format was as follows -
myIndex int identity(1,1) NOT NULL
number int NOT NULL
First one is ROW_NUMBER()...
WITH rn AS (SELECT *, ROW_NUMBER() OVER (ORDER BY myIndex) AS rn, COUNT(*) AS max
FROM counting c GROUP BY c.myIndex, c.number)
,cte (myIndex, number, level, row) AS (
SELECT r.myIndex, r.number, 1, r.rn + 1 FROM rn r WHERE r.rn = 1
UNION ALL
SELECT r1.myIndex, r1.number,
CASE WHEN r1.number = 0 AND r2.number = 1 THEN 1
ELSE c.level + 1
END,
row + 1
FROM cte c
JOIN rn r1
ON c.row = r1.rn
JOIN rn r2
ON c.row - 1 = r2.rn
)
SELECT c.myIndex, c.number, c.level FROM cte c OPTION (MAXRECURSION 0);
Now the index...
WITH cte (myIndex, number, level) AS (
SELECT c.myIndex + 1, c.number, 1 FROM counting c WHERE c.myIndex = 1
UNION ALL
SELECT c1.myIndex + 1, c1.number,
CASE WHEN c1.number = 0 AND c2.number = 1 THEN 1
ELSE c.level + 1
END
FROM cte c
JOIN counting c1
ON c.myIndex = c1.myIndex
JOIN counting c2
ON c.myIndex - 1 = c2.myIndex
)
SELECT c.myIndex - 1 AS myIndex, c.number, c.level FROM cte c OPTION (MAXRECURSION 0);

Answer 3

The answer that I have now is via using
Cursor
I know if there is another solution without cursor it will be better for performance aspects
here is a quick demo of my solution:
-- Create DBTest
use master
Go
Create Database DBTest
Go
use DBTest
GO
-- Create table
Create table Tabletest
(nInd int , eq int)
Go
-- insert dummy data
insert into Tabletest (nInd,eq)
values (1,0),
(2,1),
(3,0),
(4,1),
(5,0),
(6,0),
(7,0),
(8,0),
(9,1),
(8,0),
(9,1)
Create table #Tabletest (nInd int ,eq int ,x int )
go
DECLARE #nInd int , #eq int , #x int
set #x = 1
DECLARE db_cursor CURSOR FOR
SELECT nInd , eq
FROM Tabletest
order by nInd
OPEN db_cursor
FETCH NEXT FROM db_cursor INTO #nInd , #eq
WHILE ##FETCH_STATUS = 0
BEGIN
if (#eq = 0)
begin
insert into #Tabletest (nInd ,eq ,x) values (#nInd , #eq , #x)
set #x = #x +1
end
else if (#eq = 1)
begin
insert into #Tabletest (nInd ,eq ,x) values (#nInd , #eq , #x)
set #x = 1
end
FETCH NEXT FROM db_cursor INTO #nInd , #eq
END
CLOSE db_cursor
DEALLOCATE db_cursor
select * from #Tabletest
The end result set will be as following:
Hope it helps.

Answer 4

Looking at this a slightly different way (which might not be true, but eliminates the need for cursors of recursive CTEs), it looks like you building ordered groups within your dataset. So, start by finding those groups, then determining the ordering of each of them.
The real key is to determine the rules to find the correcting grouping. Based on your description and comments, I'm guessing the grouping is from the start (ordered by the nInd column) ending at each row with and eq value of 1, so you can do something like:
;with ends(nInd, ord) as (
--Find the ending row for each set
SELECT nInd, row_number() over(order by nInd)
FROM mytable
WHERE eq=1
), ranges(sInd, eInd) as (
--Find the previous ending row for each ending row, forming a range for the group
SELECT coalesce(s.nInd,0), e.nInd
FROM ends s
right join ends e on s.ord=e.ord-1
)
Then, using these group ranges, you can find the final ordering of each:
select t.nInd, t.Fecha, t.eq
,[x] = row_number() over(partition by sInd order by nInd)
from ranges r
join mytable t on r.sInd < t.nInd
and t.nInd <= r.eInd
order by t.nInd