SQL - AVG Output is incorrect - sql

Question

In below query, I am calculating the lead time between two different dates and eventually trying to get the average of that lead time but the output is incorrect.
SELECT
Round(AVG(CAST(
Case when CONVERT(datetime, ORDERDATE, 105) = CONVERT(datetime, INVOUTDATE, 105) THEN 0 else
Case when CONVERT(datetime, ORDERDATE, 105) + 1 = CONVERT(datetime, INVOUTDATE, 105) THEN 1 else
(DATEDIFF(dd, CONVERT(datetime, ORDERDATE, 105), CONVERT(datetime, INVOUTDATE, 105)))
-(DATEDIFF(wk, CONVERT(datetime, ORDERDATE, 105), CONVERT(datetime, INVOUTDATE, 105))*1)
-(CASE WHEN DATENAME(dw, CONVERT(datetime, ORDERDATE, 105)) = 'Sunday' THEN 1 ELSE 0 END)
-(CASE WHEN DATENAME(dw, CONVERT(datetime, INVOUTDATE, 105)) = 'Sunday' THEN 0 ELSE 0 END) end end AS FLOAT)),4) AS LEADTIME FROM DSORDERSTATUS
WHERE ORDERTYPE <> 'Exchange Order'
AND CONVERT(datetime, ORDERDATE, 105) between '20170801' and '20170831'
AND CONVERT(datetime, INVOUTDATE, 105) IS NOT NULL
To troubleshoot the above query I extract the data by using the same query below and when I manually calculate the lead time and average it was correct.
Don't know where is the issue? can someone please tell me whether anything wrong with my query.
Please click on the link to refer sample data Link
SELECT DISTINCT DOCKETNO,
Case when CONVERT(datetime, ORDERDATE, 105) = CONVERT(datetime, INVOUTDATE, 105) THEN 0 else
Case when CONVERT(datetime, ORDERDATE, 105) + 1 = CONVERT(datetime, INVOUTDATE, 105) THEN 1 else
(DATEDIFF(dd, CONVERT(datetime, ORDERDATE, 105), CONVERT(datetime, INVOUTDATE, 105)))
-(DATEDIFF(wk, CONVERT(datetime, ORDERDATE, 105), CONVERT(datetime, INVOUTDATE, 105))*1)
-(CASE WHEN DATENAME(dw, CONVERT(datetime, ORDERDATE, 105)) = 'Sunday' THEN 1 ELSE 0 END)
-(CASE WHEN DATENAME(dw, CONVERT(datetime, INVOUTDATE, 105)) = 'Sunday' THEN 0 ELSE 0 END) end end AS LEADTIME FROM DSORDERSTATUS
WHERE ORDERTYPE <> 'Exchange Order'
AND CONVERT(datetime, ORDERDATE, 105) between '20170801' and '20170831'
AND CONVERT(datetime, INVOUTDATE, 105) IS NOT NULL

Answer 1

ok, now I understand..
I think you have to group by orders before to calculate avg
;with
S AS (
select DOCKETNO, ORDERDATE, INVOUTDATE, COUNT(*) n
from DSORDERSTATUS where ORDERTYPE <> 'Exchange Order'
group by DOCKETNO, ORDERDATE, INVOUTDATE
),
D as (
select [DOCKETNO], [ORDERDATE], [INVOUTDATE],
DATEDIFF(dd, CONVERT(date, [ORDERDATE], 105), CONVERT(date, [INVOUTDATE], 105)) dd,
DATEDIFF(wk, CONVERT(date, [ORDERDATE], 105), CONVERT(date, [INVOUTDATE], 105)) wk,
CASE WHEN DATEPART(dw, CONVERT(datetime, ORDERDATE, 105)) = 7 THEN 1 ELSE 0 END IsSundayOrd,
CASE WHEN DATEPART(dw, CONVERT(datetime, INVOUTDATE, 105)) = 7 THEN 1 ELSE 0 END IsSundayInv
from S
)
select avg(cast(dd - case when dd>1 then (wk + IsSundayOrd + IsSundayInv) else 0 end as float)) leadtime
from D
where CONVERT(date, ORDERDATE, 105) between '20170801' and '20170831'
AND CONVERT(date, INVOUTDATE, 105) IS NOT NULL

Answer 2

I will try to convert your dates to DATE instesad of DATETIME I think you are filtering too much rows because '20170831' is '2017-08-31 00:00:00' and you are loosing all ORDERDATE between '00:00:00' and '23:59:59' (for '2017-08-31')
WHERE ORDERTYPE <> 'Exchange Order'
AND CONVERT(date, ORDERDATE, 105) between '20170801' and '20170831'
AND CONVERT(date, INVOUTDATE, 105) IS NOT NULL

Answer 3

With the help of MtwStark i was able to resolve this.
I have modified his query,
Thanks buddy
;with
S AS (
SELECT DISTINCT DOCKETNO,
Case when CONVERT(datetime, ORDERDATE, 105) = CONVERT(datetime, INVOUTDATE, 105) THEN 0 else
Case when CONVERT(datetime, ORDERDATE, 105) + 1 = CONVERT(datetime, INVOUTDATE, 105) THEN 1 else
(DATEDIFF(dd, CONVERT(datetime, ORDERDATE, 105), CONVERT(datetime, INVOUTDATE, 105)))
-(DATEDIFF(wk, CONVERT(datetime, ORDERDATE, 105), CONVERT(datetime, INVOUTDATE, 105))*1)
-(CASE WHEN DATENAME(dw, CONVERT(datetime, ORDERDATE, 105)) = 'Sunday' THEN 1 ELSE 0 END)end end AS LEADTIME FROM DSORDERSTATUS
WHERE ORDERTYPE <> 'Exchange Order'
AND CONVERT(datetime, ORDERDATE, 105) between '20170801' and '20170808'
AND CONVERT(datetime, INVOUTDATE, 105) IS NOT NULL
),
D AS (
SELECT DOCKETNO, LEADTIME FROM S
)
SELECT AVG(CAST(LEADTIME AS FLOAT)) FROM D