Total number calculations - sql

Question

I am writing a stored procedure with using following data and SQL. When I execute the below SQL, I am getting the count for every month, but I want the count to add up when I do for next month. I want to add an extra column to the query (Totalcount) and I'm expecting the results as shown below. Thanks in advance!
Month_NUMBER MonthlyCount Totalcount
--------------------------------------
1 4 4
2 1 5
3 1 6
4 2 8
Here is the SQL I'm currently using:
drop table #test
create table #test (name varchar(10), MON_NUMBER int)
insert into #test
values ('XYZ', 1), ('ABC', 1), ('AZZ', 1), ('BCC', 1),
('HAS', 2), ('MRD', 3), ('GIV', 4), ('GIVE', 4)
SELECT
MON_NUMBER,
COUNT(NAME) AS MonthlyCount
FROM
#test
GROUP BY
MON_NUMBER

Answer 1

You can use your query as below:
Select *, Sum(MonthlyCount) over(order by Mon_nUmber) from (
SELECT MON_NUMBER, COUNT(NAME) AS MonthlyCount
FROM #test
group by MON_NUMBER
) a
Output as below:
+------------+--------------+------------+
| MON_NUMBER | MonthlyCount | TotalCount |
+------------+--------------+------------+
| 1 | 4 | 4 |
| 2 | 1 | 5 |
| 3 | 1 | 6 |
| 4 | 2 | 8 |
+------------+--------------+------------+

Answer 2

You can use a self-join in SQL Server 2008:
WITH CTE AS (
SELECT MON_NUMBER, COUNT(NAME) AS MonthlyCount
FROM #test
group by MON_NUMBER
)
SELECT C1.MON_NUMBER, C1.MonthlyCount, SUM(C2.MonthlyCount) AS TotalCount
FROM CTE C1
JOIN CTE C2 ON C1.MON_NUMBER >= C2.MON_NUMBER
GROUP BY C1.MON_NUMBER, C1.MonthlyCount
ORDER BY C1.MON_NUMBER, C1.MonthlyCount;

Answer 3

A window function would work here - give this a whirl.
SELECT DISTINCT
MON_NUMBER,
COUNT(NAME) AS MonthlyCount,
COUNT(name) OVER (ORDER BY mon_number)
FROM #test
group by MON_NUMBER, NAME
Order by MON_NUMBER
Windowing documentation: https://learn.microsoft.com/en-us/sql/t-sql/queries/select-over-clause-transact-sql

Answer 4

#S.Yang has already given the best and proper answer. Since SUM() window function cannot be used in SQL Server 2008, you have to use self join. Based on his answer I am submitting another solution which is useful for huge datasets by not using CTE.
IF OBJECT_ID(N'dbo.temp', N'U') IS NOT NULL DROP TABLE dbo.temp;
SELECT MON_NUMBER, COUNT(NAME) AS MonthlyCount
INTO dbo.temp
FROM #test
GROUP BY MON_NUMBER;
-- Create Index
CREATE INDEX IX_dbo_temp ON dbo.temp (MON_NUMBER, MonthlyCount);
SELECT t1.MON_NUMBER, t1.MonthlyCount, SUM(t2.MonthlyCount) AS TotalCount
FROM dbo.temp AS t1
INNER JOIN dbo.temp AS t2 ON (t2.MON_NUMBER <= t1.MON_NUMBER)
GROUP BY t1.MON_NUMBER, t1.MonthlyCount;
-- Drop temporary tables
IF OBJECT_ID(N'dbo.temp', N'U') IS NOT NULL DROP TABLE dbo.temp;