Calculate average days between two dates

I have the following table:

Team	PhoneNumber	OrderNo	CallDate	OrderDate
TM1	2222222222	26699443	2021-01-28	2021-02-05
TM1	1111111111	26699450	2021-01-22	2021-01-22
TM2	5555555555	26699466	2021-02-22	2021-02-23
TM2	5555555555	26699467	2021-01-22	2021-02-01
TM3	7777777777	26699488	2020-12-10	2021-01-03

I want to calculate the average time from call to order for each team for each month. This is my query:

SELECT 
    Team,
    MONTH(CallDate),
    AVG(DATEDIFF(day,CallDate,OrderDate))
FROM MyTab AS C 
GROUP BY Team, MONTH(CallDate)

I want to calculate the difference between the CallDate and the OrderDate and then apply the Average for each team for each month.

Answer

There is no time part in the data so how you are planning to calculate time? Do you want to multiply number of days with 24 or 8 (official time)? Please mention. If orderdate and calldate are same date then day will be 0 or one? I have considered it as 1 day.

To calculate day difference:

SELECT 
    Team,
    format(CallDate,'yyyy-MMMM') Month,
    AVG(DATEDIFF(day,CallDate,OrderDate)+1) AverageDayTaken
FROM MyTab AS C 
GROUP BY Team, format(CallDate,'yyyy-MMMM')

Output:

To calculate working hour difference(8 hour per day):

SELECT 
    Team,
    format(CallDate,'yyyy-MMMM') Month,
    AVG(DATEDIFF(day,CallDate,OrderDate)+1)*8 AverageWorkingHourTaken
FROM MyTab AS C 
GROUP BY Team, format(CallDate,'yyyy-MMMM')