Calculating Early and Late Dates for Performance Measurement - sql-server

Question

I am trying to calculate shipping performance in SSMS- Im getting stuck in several areas and I hope i can get some help!
I have an Estimated Ship Date, an Appt Date, and an Actual Ship date.
Im measuring warehouse performance, so in most cases shipments leave same day. But in others, they may leave a few days early or late.
The problem that i am having is the correct output. I want to show the Values in DD:HH:MM, but the syntax for DateDiff doesn't give me an accurate day to use:
For Example, a shipment was supposed to leave on 6/3/2019 # at 8 am, but didnt leave the warehouse until 7/22/2019 # 6:30 AM. In this case, DateDiff calcs 49 days, when really its 48 days 22 hours and 30 minutes late. Here is an example of some of the syntax i am using:
EstimatedShipDate datetime,
AppointmentShipDate datetime,
ActualShipDate datetime
);
insert into #test values ('2019-07-01 11:00', '2019-07-01 11:00','2019-06-30 10:30');
insert into #test values ('2019-07-08 13:45', null,'2019-07-01 22:00');
insert into #test values ('2019-07-09 15:00', null,'2019-07-10 15:00');
insert into #test values ('2019-07-03 15:00', null,'2019-07-04 15:00');
insert into #test values ('2019-07-08 15:00', null,'2019-07-08 15:00');
insert into #test values ('2019-07-08 15:00', null,'2019-07-08 22:00');
insert into #test values ('2019-07-03 08:00', null,'2019-07-04 15:00');
insert into #test values ('2019-07-03 08:00', null,'2019-07-03 06:30');
insert into #test values ('2019-06-03 08:00', null,'2019-07-22 06:30');
insert into #test values ('2019-07-01 11:00', null,'2019-06-29 10:30');
Select
EstimatedShipDate,
AppointmentShipDate,
ActualShipDate,
DATEDIFF(DAY,ISNULL(CAST(AppointmentShipDate as DateTime),CAST(EstimatedShipDate as DateTime)), CAST(ActualShipDate as DateTime)) as Days,
DATEPART(DAY, ISNULL(CAST(AppointmentShipDate as DateTime),CAST(EstimatedShipDate as DateTime))-CAST(ActualShipDate as DateTime) ) as days2,
DATEDIFF(Hour,ISNULL(CAST(AppointmentShipDate as DateTime),CAST(EstimatedShipDate as DateTime)), CAST(ActualShipDate as DateTime)) as Hours,
convert(varchar, CAST(ActualShipDate as DateTime)-ISNULL(CAST(AppointmentShipDate as DateTime),CAST(EstimatedShipDate as DateTime)),108) as DateSubtract_Convert,
convert(varchar,ISNULL(CAST(AppointmentShipDate as DateTime),CAST(EstimatedShipDate as DateTime)-CAST(ActualShipDate as DateTime) ),108) as DateSubtract_ConvertEarly
from #TEST
In this case, DateDiff calcs 49 days, when really its 48 days 22 hours and 30 minutes late. Or vice versa, I have a date range that shows 2 days 23:20 but it should be 1 day 23:20

Answer 1

One way is to increase granularity of DATEDIFF to MINUTE. That will require calculation for the days, hours, and minutes using the minutes (division and mod).
SELECT ABS(dT.diff_Minutes / 1440) AS [Days] --days, there are 1440 minutes in a day
,ABS((dT.diff_Minutes % 1440) / 60) AS [Hours] --hours remaining in the day
,ABS((dT.diff_Minutes % 1440) % 60) AS [Minutes] --minutes remaining in the day
FROM (
SELECT DATEDIFF(MINUTE, ISNULL(AppointmentShipDate, EstimatedShipDate), ActualShipDate) [diff_Minutes]
FROM #test
) AS dT
Your temp table produces output:
Days Hours Minutes
1 0 30
6 15 45
1 0 0
1 0 0
0 0 0
0 7 0
1 7 0
0 1 30
48 22 30
2 0 30
To put these in DD:HH:MM format is more complicated, but you can cast the numbers to varchar and concatenate as strings. RIGHT is used to add any leading zeroes.
SELECT CASE WHEN dT.diff_Minutes < 0 THEN '- ' ELSE '+ ' END --positive or negative
+ RIGHT('00' + CAST(ABS(dT.diff_Minutes / 1440) as varchar(1000)), 2)
+ ':'
+RIGHT('00' + CAST((ABS(dT.diff_Minutes % 1440) / 60) as varchar(2)), 2)
+ ':'
+RIGHT('00' + CAST((ABS(dT.diff_Minutes % 1440) % 60) as varchar(2)), 2)
AS [DD:HH:MM]
FROM (
SELECT DATEDIFF(MINUTE, ISNULL(AppointmentShipDate, EstimatedShipDate), ActualShipDate) [diff_Minutes]
FROM #test
) AS dT
Produces output:
DD:HH:MM
- 01:00:30
- 06:15:45
+ 01:00:00
+ 01:00:00
+ 00:00:00
+ 00:07:00
+ 01:07:00
- 00:01:30
+ 48:22:30
- 02:00:30

Answer 2

Use seconds instead of days and then do a little math with seconds, minutes and hours.
Here's a simple SSMS example:
DECLARE
#ScheduledDate DATETIME = '6/3/2019 08:00:00',
#ShippedDate DATETIME = '07/22/2019 06:30:00';
SELECT
CONVERT( VARCHAR, DATEDIFF( s, #ScheduledDate, #ShippedDate ) /60/60/24 ) + ' Days and '
+ CONVERT( VARCHAR, ( #ShippedDate - #ScheduledDate ), 108 ) + ' Hours.';
Returns
48 Days and 22:30:00 Hours.