Month Difference Without additional table - sql-server

Question

I am new to SQL query world and got stuck into one requirement.
In my Query i have toDate and fromdate input parameter, based on business logic it will return result like below.
Result:-
Month
Dec-16
Dec-16
Dec-16
Feb-17
Feb-17
Mar-17
Mar-17
now query should need to return the data for each month , if we dont have data for perticular month(in image which is Jan) then it should insert data and return data for that month too, in image we can see for Jan we dont have any data.

Answer 1

You can use a calendar or dates table for this sort of thing.
Without a calendar table, you can generate an adhoc set of months using a common table expression with just this:
declare #fromdate date = '20161201';
declare #todate date = '20170301';
;with n as (select n from (values(0),(1),(2),(3),(4),(5),(6),(7),(8),(9)) t(n))
, Months as (
select top (datediff(month, #fromdate, #todate)+1)
[Month]=convert(date,dateadd(month,row_number() over(order by (select 1))-1,#fromdate))
from n as deka cross join n as hecto cross join n as kilo
order by [Month]
)
/* your query here: */
select
d.[Month]
, sum_col = sum(t.col)
from Months
left join tbl t
on d.[Month] = t.[Month]
group by d.[Month]
Number and Calendar table reference:
Generate a set or sequence without loops - 2 - Aaron Bertrand
The "Numbers" or "Tally" Table: What it is and how it replaces a loop - Jeff Moden
Creating a Date Table/Dimension in sql Server 2008 - David Stein
Calendar Tables - Why You Need One - David Stein
Creating a date dimension or calendar table in sql Server - Aaron Bertrand

Answer 2

Solved Query:-
Declare #customDate DATETIME
declare #datafound integer
set #customDate = #fromDate
WHILE #customDate < #toDate
BEGIN
select #datafound = count(1) from #temp where datepart(month, MonthDate) = datepart(month, #customDate)
if #datafound = 0
select Format(#customDate,'MMM-yy') as Month
SET #customDate = DATEADD(month, 1,#customDate)
END;