SQL 累计计数

Question

I have table with departments. I need to count how many people are within which dept. This is easily done by

SELECT DEPT,
       COUNT(*) as 'Total'
    FROM SR
    GROUP BY DEPT;

Now I need to also do cumulative count as below:

I have found some SQL to count running total, but not case like this one. Could you provide me some advice in this case, please?

Answer 1

Here's a way to do it with a CTE instead of a cursor:

WITH Base AS
(
    SELECT ROW_NUMBER() OVER (ORDER BY [Count] DESC) RowNum,
    [Dept],
    [Count]
    FROM SR
)
SELECT SR.Dept, SR.Count, SUM(SR2.[Count]) Total
FROM Base SR
INNER JOIN Base SR2
    ON SR2.RowNum <= SR.RowNum
GROUP BY SR.Dept, SR.Count
ORDER BY SR.[Count] DESC

Note that this is ordering by descending Count like your sample result does. If there's some other column that's not shown that should be used for ordering just replace Count in each of the ORDER BY clauses.

SQL Fiddle Demo

Answer 2

I think you can use some temporary / variable table for this, and use solution from here :

declare @Temp table (rn int identity(1, 1) primary key, dept varchar(128), Total int)

insert into @Temp (dept, Total)
select
    dept, count(*) as Total
from SR
group by dept

;with cte as (
    select T.dept, T.Total, T.Total as Cumulative, T.rn
    from @Temp as T
    where T.rn = 1
    union all
    select T.dept, T.Total, T.Total + C.Cumulative as Cumulative, T.rn
    from cte as C
        inner join @Temp as T on T.rn = C.rn + 1
)
select C.dept, C.Total, C.Cumulative
from cte as C
option (maxrecursion 0)

sql fiddle demo

There're some other solutions, but this one is fastest for SQL Server 2008, I think.

Answer 3

If it is possible to add an identity column to the table - then the solution is easier;

create table #SQLCumulativeCount
(
 id int identity(1,1),
 Dept varchar(100),
 Count int
)
insert into #SQLCumulativeCount (Dept,Count) values ('PMO',106)
insert into #SQLCumulativeCount (Dept,Count) values ('Finance',64)
insert into #SQLCumulativeCount (Dept,Count) values ('Operations',41)
insert into #SQLCumulativeCount (Dept,Count) values ('Infrastructure',22)
insert into #SQLCumulativeCount (Dept,Count) values ('HR',21)

select *,
   sum(Count) over(order by id rows unbounded preceding) as Cumulative 
from #SQLCumulativeCount

Answer 4

with Base as (
select 
    dept, 
    count, 
    ROW_NUMBER() OVER(order by count desc) as RowNum
from SR
)
select 
    dept, 
    count, 
    sum(count) over(order by RowNum) as Cumulative
from Base