I have a table Temp:
x
CREATE TABLE Temp
(
[ID] [int],
[Year] [INT],
)
**ID Year**
1 2016
1 2016
1 2015
1 2012
1 2011
1 2010
2 2016
2 2015
2 2014
2 2012
2 2011
2 2010
2 2009
3 2016
3 2015
3 2004
3 1999
4 2016
4 2015
4 2014
4 2010
5 2016
5 2014
5 2013
I want to calculate the total consecutive years starting from the most recent Year. Result should look like this:
ID Total Consecutive Yrs
1 2
2 3
3 2
4 3
5 1
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Answer
select ID,
-- returns a sequence without gaps for consecutive years
first_value(year) over (partition by ID order by year desc) - year +1 as x,
-- returns a sequence without gaps
row_number() over (partition by ID order by year desc) as rn
from Temp
e.g. for ID=1:
1 2016 1 1
1 2015 2 2
1 2012 5 3
1 2011 6 4
1 2010 7 5
As long as there’s no gap, both sequences increase the same.
Now check for equal sequences and count the rows:
with cte as
(
select ID,
-- returns a sequence without gaps for consecutive years
first_value(year) over (partition by ID order by year desc) - year + 1 as x,
-- returns a sequence without gaps
row_number() over (partition by ID order by year desc) as rn
from Temp
)
select ID, count(*)
from cte
where x = rn -- no gap
group by ID
Edit:
Based on your year zero comment:
with cte as
(
select ID, year,
-- returns a sequence without gaps for consecutive years
first_value(year) over (partition by ID order by year desc) - year + 1 as x,
-- returns a sequence without gaps
row_number() over (partition by ID order by year desc) as rn
from Temp
)
select ID,
-- remove the year zero from counting
sum(case when year <> 0 then 1 else 0 end)
from cte
where x = rn
group by ID