Get attendance by month name - sql-server

Question

I am trying to find attendance for any month like this:
DECLARE #StartDate DATE
DECLARE #EndDate DATE
SET #StartDate = '2016/10/01'
SET #EndDate = '2016/10/31'
SELECT
StaffAttendance.StaffId, DATENAME(MONTH, #StartDate) AS [ForMonth],
(DATEDIFF(dd, #StartDate, #EndDate) + 1)
-(DATEDIFF(wk, #StartDate, #EndDate) * 1)
-(CASE WHEN DATENAME(dw, #StartDate) = 'Sunday' THEN 1 ELSE 0 END) AS TotalWorkingDays,
SUM(StaffAttendance.AttendanceStatusId) AS TotalDaysWorked FROM StaffAttendance WHERE [Date] BETWEEN #StartDate AND #EndDate AND StaffAttendance.AttendanceStatusId = 1 GROUP BY StaffAttendance.StaffId
And this is what I am getting, which is just fine.
What I want to do next is omit the date range (#StartDate DATE, #EndDate DATE) and use month name instead like - 'October' and not month number like '10.' So that user gives a month name and start and end dates for that month are automatically calculated. I got help for that by Felix Pamittan.
DECLARE #month VARCHAR(9) = 'february';
WITH CteMonths(n, m) AS(
SELECT 1, 'January' UNION ALL
SELECT 2, 'February' UNION ALL
SELECT 3, 'March' UNION ALL
SELECT 4, 'April' UNION ALL
SELECT 5, 'May' UNION ALL
SELECT 6, 'June' UNION ALL
SELECT 7, 'July' UNION ALL
SELECT 8, 'August' UNION ALL
SELECT 9, 'September' UNION ALL
SELECT 10, 'October' UNION ALL
SELECT 11, 'November' UNION ALL
SELECT 12, 'December'
)
SELECT
DATEADD(MONTH, n - 1, DATEADD(YEAR, DATEDIFF(YEAR, 0, GETDATE()), 0)) AS StartDate,
DATEADD(DAY, -1, DATEADD(MONTH, n, DATEADD(YEAR, DATEDIFF(YEAR, 0, GETDATE()), 0))) AS EndDate
FROM CteMonths
WHERE m = #month
Now, how do I combine these two and get same result as above?

Answer 1

Use CROSS APPLY:
DECLARE #month VARCHAR(9) = 'february';
WITH CteMonths(n, m) AS(
SELECT 1, 'January' UNION ALL
SELECT 2, 'February' UNION ALL
SELECT 3, 'March' UNION ALL
SELECT 4, 'April' UNION ALL
SELECT 5, 'May' UNION ALL
SELECT 6, 'June' UNION ALL
SELECT 7, 'July' UNION ALL
SELECT 8, 'August' UNION ALL
SELECT 9, 'September' UNION ALL
SELECT 10, 'October' UNION ALL
SELECT 11, 'November' UNION ALL
SELECT 12, 'December'
)
SELECT
sa.StaffId,
DATENAME(MONTH, t.StartDate) AS [ForMonth],
(DATEDIFF(dd, t.StartDate, t.EndDate) + 1)
- (DATEDIFF(wk, t.StartDate, t.EndDate) * 1)
- (CASE WHEN DATENAME(dw, t.StartDate) = 'Sunday' THEN 1 ELSE 0 END) AS TotalWorkingDays,
SUM(sa.AttendanceStatusId) AS TotalDaysWorked
FROM StaffAttendance sa
CROSS APPLY(
SELECT
DATEADD(MONTH, n - 1, DATEADD(YEAR, DATEDIFF(YEAR, 0, GETDATE()), 0)) AS StartDate,
DATEADD(DAY, -1, DATEADD(MONTH, n, DATEADD(YEAR, DATEDIFF(YEAR, 0, GETDATE()), 0))) AS EndDate
FROM CteMonths
) t
WHERE
sa.[Date] >= t.StartDate
AND sa.[Date] < DATEADD(DAY, 1, t.EndDate)
AND sa.AttendanceStatusId = 1
GROUP BY sa.StaffId