Select missing months between 2 dates (in same year) - sql-server

Question

I'm trying to get all months in which no transaction is placed for the same year (If different years is not possible)
This is my query to get transactions between 2 dates, but don't know how can I select only months for which transaction in database is missing
SELECT *
FROM Installment
WHERE OrderId = 1
AND InstallmentDate
BETWEEN cast('8/02/2014' as date)
AND cast('12/25/2014' as date)
InstallmentId OrderId CustomerKey InstallmentAmount InstallmentDate
18 1 INS-1 3000 2014-09-03
92 1 INS-1 3000 2014-10-13
137 1 INS-1 3000 2014-11-05
in this case record for the 12th month and 8th month is missing, how can I get this with SQL Server Query ?
Update
select yymm.yy, yymm.mm
from (select distinct year(InstallmentDate) as yy, month(InstallmentDate) as mm
from Installment
where InstallmentDate BETWEEN '2014-09-02' and '2015-01-15'
) yymm left join
Installment i
on i.OrderId = 1 and
year(i.InstallmentDate) = yymm.yy and
month(i.InstallmentDate) = yymm.mm
where i.OrderId is not null;
Gordon's query is returning all the years and months from table between 2 dates, just by changing i.OrderId is null to i.OrderId is not null here is the out of his query
yy mm
2014 9
2014 10
2014 11
Expected Output (if possible)
yy mm
2014 12
2015 1

Answer 1

Using the following recursive CTE:
DECLARE #start DATE = '2014-09-02'
DECLARE #end DATE = '2015-01-15'
;WITH IntervalDates (date)
AS
(
SELECT #start
UNION ALL
SELECT DATEADD(MONTH, 1, date)
FROM IntervalDates
WHERE DATEADD(MONTH, 1, date)<=#end
)
SELECT YEAR(date) AS Year, MONTH(date) AS Month
FROM IntervalDates
you can get a list of all Years/Months between the two dates of interest:
Year Month
==============
2014 9
2014 10
2014 11
2014 12
2015 1
Using EXCEPT on the above CTE:
;WITH IntervalDates (date)
AS
(
SELECT #start
UNION ALL
SELECT DATEADD(MONTH, 1, date)
FROM IntervalDates
WHERE DATEADD(MONTH, 1, date)<=#end
)
SELECT YEAR(date) AS Year, MONTH(date) AS Month
FROM IntervalDates
EXCEPT
SELECT DISTINCT YEAR(InstallmentDate) AS yy, MONTH(InstallmentDate) AS mm
FROM Installment
WHERE OrderId = 1 AND InstallmentDate BETWEEN #start AND #end
yields the required result set:
Year Month
=============
2014 12
2015 1

Answer 2

To do this in SQL, you need to start with a list of months. Assuming you have at least one record for each month in the table, you can then get the missing dates easily using a subquery. The rest of the query is just a left join and checking for non-matches:
select yymm.yy, yymm.mm
from (select distinct year(InstallmentDate) as yy, month(InstallmentDate) as mm
from Installment
where InstallmentDate BETWEEN '2014-09-02' and '2015-01-15'
) yymm left join
Installment i
on i.OrderId = 1 and
year(i.InstallmentDate) = yymm.yy and
month(i.InstallmentDate) = yymm.mm
where i.OrderId is null;

Answer 3

Simplest way I can think of is to have a date dimension table that contains (at least) date, and 1st of month then. For creating one take a look at something like https://dba.stackexchange.com/questions/74957/best-approach-for-populating-date-dimension-table , although that one doesn't have firstOfMonthDate in it as my example show but the idea is the same.
then your query becomes
SELECT DISTINCT
firstOfMonthDate
FROM
dateRef dr
LEFT OUTER JOIN
InstallmentDate i ON dr.date = i.InstallmentDate AND i.OrderId = 1
WHERE
i.InstallmentDate IS NULL
AND
dr.date BETWEEN #startDate and #endDate
change firstOfMonthDate for fiscal month etc. as required. This would work across any range of dates you have in your table so different years wouldn't be an issue.

Answer 4

Try the below script. I retrieve all dates between the specified dates and use a LEFT JOIN to get those which are not present in your table:
DECLARE #startDate AS DATETIME, #endDate AS DATETIME
DECLARE #dates AS TABLE (CurrentDate DATETIME)
SET #startDate = '2014-01-01'
SET #endDate = '2014-01-31';
with GetDates AS
(
SELECT #startDate AS TheDate
UNION ALL
SELECT DATEADD("DD", 1, TheDate) FROM GetDates
WHERE TheDate < #endDate
) INSERT INTO #dates SELECT TheDate FROM GetDates
OPTION (MAXRECURSION 0)
SELECT DISTINCT YEAR(d.CurrentDate), MONTH(d.CurrentDate) FROM #dates d
LEFT JOIN InstallmentDate i ON i.InstallmentDate BETWEEN #startDate AND #endDate AND OrderId = 1
WHERE i.InstallmentDate IS NULL
Hope this helps...