Find groups containing 6 consecutive 1s in one column - sql

Question

I have a table with 2 columns:
val with values: 0 or 1
id with unique identifiers
with cte(val, id) as (
select 0, 0 union all
select 1, 1 union all
select 1, 2 union all
select 0, 3 union all
select 1, 4 union all
select 1, 5 union all
select 1, 6 union all
select 1, 7 union all
select 1, 8 union all
select 1, 9 union all
select 1, 10
)
select *
into #tmp
from cte
How do I to find id with 6 values = 1 in a row.
In the example above: id = 9, id = 10.
It is desirable not to use loops (cursors or while), but something like sum(...) over(...).

Answer 1

Why not LAG() (but you need an order column):
SELECT id
FROM (
SELECT
id,
val,
val1 = LAG(val, 1) OVER (ORDER BY id),
val2 = LAG(val, 2) OVER (ORDER BY id),
val3 = LAG(val, 3) OVER (ORDER BY id),
val4 = LAG(val, 4) OVER (ORDER BY id),
val5 = LAG(val, 5) OVER (ORDER BY id)
FROM YourTable
) t
WHERE val = 1 AND val1 = 1 AND val2 = 1 AND val3 = 1 AND val4 = 1 AND val5 = 1

Answer 2

You can use running sum over a window frame that contains exactly 6 rows (5 prior plus current row):
with cte as (
select *, sum(val) over (
order by id
rows between 5 preceding and current row
) as rsum
from #tmp
)
select *
from cte
where rsum = 6
Adjust the size of the window and where clause to match the desired value.

Answer 3

Another approach is using ROW_NUMBER on the LAG values
declare #tmp table (val int, id int)
insert into #tmp values
(0, 0), (1, 1), (1, 2), (0, 3), (1, 4), (1, 5), (1, 6), (1, 7), (1, 8), (1, 9), (1, 10)
select 0, 0 union all
select 1, 1 union all
select 1, 2 union all
select 0, 3 union all
select 1, 4 union all
select 1, 5 union all
select 1, 6 union all
select 1, 7 union all
select 1, 8 union all
select 1, 9 union all
select 1, 10
select t2.id,
t2.islandcount
from ( select t.id,
t.val,
t.priorval,
row_number() over (partition by t.val, t.priorval order by t.id) as islandcount
from ( select id,
val,
lag(val, 1) over (order by id) priorval
from #tmp
) t
) t2
where t2.islandcount >= 6
the result is
id islandcount
9 6
10 7
Try it yourself in this DBFiddle
The advantage of this method is that you can easy set the value from 6 to any other value
EDIT
As #Zhorov mentioned in the comment, there is a flaw in my code, it returns the wrong results when you add certain rows
This solution will fix that, it is based on the solution of #SalmanA so the credit for accepted answer should go to him
declare #tmp table (val int, id int)
insert into #tmp values
(0, 0), (1, 1), (1, 2), (0, 3), (1, 4), (1, 5), (1, 6), (1, 7), (1, 8), (1, 9), (1, 10)
-- these are the certains rows added
,(0, 11), (1, 12), (1, 13)
select t.id,
t.val,
t.islandcount
from ( select id,
val,
sum(val) over (order by id rows between 5 preceding and current row) as islandcount
from #tmp
) t
where t.islandcount >= 6
order by t.id
And again a DBFiddle