SQL Query Group By Mount And Year - sql

Question

I have this table, called history (dates are in DD-MM-YYYY):
====================
| Buy | Qty |
====================
| 01-01-2012 | 1 |
| 01-01-2012 | 1 |
| 01-02-2012 | 1 |
| 01-03-2012 | 1 |
| 01-05-2012 | 1 |
| 01-07-2012 | 1 |
| 01-12-2012 | 1 |
====================
NOTE: There was no purchase in months 4, 6, 8, 9, 10, 11.
If I run :
SELECT MONTH(buy) AS day, YEAR(buy) as year, SUM(qty)
FROM history
GROUP BY MONTH(buy),YEAR(buy)
I get this result:
======================
| Month | Year | Qty |
======================
| 01 | 2012 | 2 |
| 02 | 2012 | 1 |
| 03 | 2012 | 1 |
| 05 | 2012 | 1 |
| 07 | 2012 | 1 |
| 12 | 2012 | 1 |
======================
I want months 4, 6, 8, 9, 10, 11 to show too but have Qty of 0 (zero), like this:
======================
| Month | Year | Qty |
======================
| 01 | 2012 | 2 |
| 02 | 2012 | 1 |
| 03 | 2012 | 1 |
| 04 | 2012 | 0 |
| 05 | 2012 | 1 |
| 06 | 2012 | 0 |
| 07 | 2012 | 1 |
| 08 | 2012 | 0 |
| 09 | 2012 | 0 |
| 10 | 2012 | 0 |
| 11 | 2012 | 0 |
| 12 | 2012 | 1 |
======================
How can I do this?

Answer 1

Try this :
Declare #Sample table
(Buy datetime ,Qty int)
Insert into #Sample values
( '01-01-2012' ,1),
('01-01-2012',1 ),
('01-02-2012',1 ),
('01-03-2012',1 ),
('01-05-2012',1 ),
('01-07-2012',1 ),
('01-12-2012',1 )
;with cte as
(
select top 12 row_number() over(order by t1.number) as N
from master..spt_values t1
cross join master..spt_values t2
)
select t.N as month,
isnull(datepart(year,y.buy),'2012') as Year,
sum(isnull(y.qty,0)) as Quantity
from cte t
left join #Sample y
on month(convert(varchar(20),buy,103)) = t.N
group by y.buy,t.N
Create a Month table to store the value from 1 to 12 .Instead of master..spt_values you can also use sys.all_objects
select row_number() over (order by object_id) as months
from sys.all_objects
or use a recursive cte to generate the month table
;with cte(N) as
(
Select 1
union all
Select 1+N from cte where N<12
)
Select * from cte
and then use Left join to compare the value from the month table with your table and use isnull function to handle the null values.

Answer 2

You could use a look-up table of integers.
What I use in this situation is a function/procedure that generates the number via a CTE (Example below)
The rest would be to create dates using the resulting number as the month - and then join your results from above.
declare #min int
declare #max int
set #min = 1
set #max = 12
;
with numbers(n) as
(
select #min as n
union all
select n + 1
from numbers
where n + 1 <= #max
)
select row_number() over (order by n) [row], n
from numbers option(maxrecursion 0);

Answer 3

Below code will helps you, you can also filter data by year
SELECT MonthYearTable.Month , MonthYearTable.Year, ISNULL(SUM(qty),0)
FROM history
Right JOIN (SELECT Month, Year FROM (SELECT 1 AS Month
Union SELECT 2
Union SELECT 3
Union SELECT 4
Union SELECT 5
Union SELECT 6
Union SELECT 7
Union SELECT 8
Union SELECT 9
Union SELECT 10
Union SELECT 11
Union SELECT 12) AS MonthTable
INNER JOIN (SELECT DISTINCT YEAR(buy) AS year FROM history) YearTable ON 1=1
) AS MonthYearTable ON Month(history.buy) = MonthYearTable.Month AND Year(history.buy) = MonthYearTable.Year
GROUP BY MonthYearTable.Month, MonthYearTable.Year
ORDER BY MonthYearTable.Year, MonthYearTable.Month

Answer 4

Try This:
CREATE TABLE history(Buy datetime,Qty int)
INSERT INTO history
VALUES('01-01-2012',1),
('01-01-2012',1),
('01-02-2012',1),
('01-03-2012',1),
('01-05-2012',1),
('01-07-2012',1),
('01-12-2012',1)
Declare #mindate datetime
Declare #maxdate datetime
select #mindate=MIN(convert(datetime,buy,103)),#maxdate=MAX(convert(datetime,buy,103)) from history
select datepart(month,a.dt) as month,datepart(year,a.dt) as year,isnull(SUM(qty),0) as Quantity
from
(select DATEADD(mm,number,convert(varchar(10),#mindate,103)) as dt from master..spt_values
where type='p' and DATEADD(mm,number,convert(varchar(10),#mindate,103)) <= convert(varchar(10),#maxdate,103)
) a left join history h
on DATEPART(month,a.dt) = DATEPART(month,convert(varchar(10),h.Buy ,103))
group by a.dt
order by a.dt