SQL Date Query include month even if no data

Question

I have a booking database with various dates for each booking. I want to get a count of all bookings in each month e.g.

JAN | 12
FEB | 15
MAR | 53
APR | 25


        

Answer 1

You need to have a table variable with all the months and do a JOIN.

DECLARE @months TABLE (MonthNumber INT, YearNumber INT, Name VARCHAR(50))

INSERT INTO @months (MonthNumber, YearNumber, Name) VALUES (1, 2015, 'January')
...


SELECT MonthNumber, YearNumber, ISNULL(SUM(...), 0)
FROM Booking b
RIGHT JOIN @months mo ON DATEPART(m, b.BookingDate)=mo.MonthNumber AND DATEPART(yy, b.BookingDate)=mo.YearNumber
GROUP BY mo.MonthNumber, mo.YearNumber

EDIT: If you want to consider multiple years, add year as a column in @month and change the CROSS JOIN condition to consider month and year.

Answer 2

The easy way is using a months table because you can have empty months.

create table months (
   month_id integer,
   date_ini datetime,
   date_end datetime
) 

And this are some examples of how create that table automatic

Using select Generate days from date range

This use store procedure in MSQL