SQL - date group by year, month, days

When I execute query

SELECT Item,
    [From date],
    [To date]
 from ItemDate;

I got this table:

('A1','2014-03-05','2014-07-21'),
('A1','2014-07-25','2015-03-15'),
('A1','2015-03-17','2016-03-17'),
('B1','2015-04-18','2016-06-16'),
('C1','2015-04-21','2016-02-12'),
('C1','2016-02-14','2016-08-29')

I want to calculate difference between date [From date] and [To date] and get next table:

Item   Year    NoOfMonth  NoOfDays
A1    2014       9          ...
A1    2015       ...        ...
........

Group by Year and item

NoOfMonts is number of months by year and item
NoOfDays is number of days by year and item.

Any idea?

You can use calendar table and some date functions:

;WITH calendar AS (
SELECT  CAST(MIN([From date]) as datetime) as d,
        MAX([To date]) as e
FROM ItemTable
UNION ALL
SELECT  DATEADD(day,1,d),
        e
FROM calendar
WHERE d < e
), cte AS(
SELECT  i.Item,
        DATEPART(year,c.d) as [Year],
        DATEDIFF(month,MIN(c.d),MAX(c.d)) as NoOfMonth,
        DATEDIFF(day,DATEADD(month,DATEDIFF(month,MIN(c.d),MAX(c.d)),MIN(c.d)),MAX(c.d)) as NoOfDays
FROM ItemTable i
INNER JOIN calendar c
    ON c.d between i.[From date] and i.[To date]
GROUP BY i.Item, DATEPART(year,c.d),[From date],[To date]
)

SELECT  Item,
        [Year],
        SUM(NoOfMonth) as NoOfMonth,
        SUM(NoOfDays) as NoOfDays
FROM cte
GROUP BY Item,[Year]
ORDER BY Item
OPTION (MAXRECURSION 0)

Output:

Item    Year    NoOfMonth   NoOfDays
A1      2014    9           22
A1      2015    11          28
A1      2016    2           16
B1      2015    8           13
B1      2016    5           15
C1      2015    8           10
C1      2016    7           26

EDIT

Inspired by this question.

SELECT  Item,
        [Year],
        CASE WHEN SUM(NoOfDays) < 0 THEN SUM(NoOfMonth)-1 
            WHEN SUM(NoOfDays) > 30 THEN SUM(NoOfMonth)+1 
            ELSE SUM(NoOfMonth) END as NoOfMonth,
        CASE WHEN SUM(NoOfDays) >= 30 THEN SUM(NoOfDays)-30 
            WHEN SUM(NoOfDays) < 0 THEN SUM(NoOfDays)+30
            ELSE SUM(NoOfDays) END as NoOfDays
FROM cte
GROUP BY Item,[Year]
ORDER BY Item
OPTION (MAXRECURSION 0)

The main problem of such report - it is hard to define what is 1 month, DATEDIFF just takes number from 2 dates and subtract one from another.

I have choose 30 as a days count in month, and now I compare values of days with 30 so we can add +1 to month if the day count goes under zero or below 30