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Read sequential duplicate values ​​in SQL

I have a table like this

ID     OrdID     Value
1      1          0     
2      2          0
3      1          1
4      2          1
5      1          1
6      2          0
7      1          0
8      2          0
9      2          1
10     1          0
11     2          0

I want to get a sequential value counter where the value is 0. Using the example above, the result will be 3 (lines 6, 7 and 8). I am using sql server 2008 r2.

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2 answers

I guess it idis unique and growing. You can get the number of consecutive values ​​using different line numbers. The following count of all sequences:

select grp, value, min(id), max(id), count(*) as cnt
from (select t.*,
             (row_number() over (order by id) - row_number() over (partition by value order by id)
             ) as grp
      from table t
     ) t
group by grp, value;

If you need the longest sequence of 0s:

select top 1 grp, value, min(id), max(id), count(*) as cnt
from (select t.*,
             (row_number() over (order by id) - row_number() over (partition by value order by id)
             ) as grp
      from table t
     ) t
group by grp, value
having value = 0
order by count(*) desc
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Query using not existsto search for sequential 0s

select top 1 min(t2.id), max(t2.id), count(*)
from mytable t
join mytable t2 on t2.id <= t.id
where not exists (
    select 1 from mytable t3
    where t3.id between t2.id and t.id
    and t3.value <> 0
)
group by t.id
order by count(*) desc

http://sqlfiddle.com/#!3/52989/3

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