Find missing date as compare to calendar - sql

Question

I am explain problem in short.
select distinct DATE from #Table where DATE >='2016-01-01'
Output :
Date
2016-11-23
2016-11-22
2016-11-21
2016-11-19
2016-11-18
Now i need to find out missing date a compare to our calender dates from year '2016'
i.e. Here date '2016-11-20' is missing.
I want list of missing dates.
Thanks for reading this. Have nice day.

Answer 1

You need to generate dates and you have to find missing ones. Below with recursive cte i have done it
;WITH CTE AS
(
SELECT CONVERT(DATE,'2016-01-01') AS DATE1
UNION ALL
SELECT DATEADD(DD,1,DATE1) FROM CTE WHERE DATE1<'2016-12-31'
)
SELECT DATE1 MISSING_ONE FROM CTE
EXCEPT
SELECT * FROM #TABLE1
option(maxrecursion 0)

Answer 2

Using CTE and get all dates in CTE table then compare with your table.
CREATE TABLE #yourTable(_Values DATE)
INSERT INTO #yourTable(_Values)
SELECT '2016-11-23' UNION ALL
SELECT '2016-11-22' UNION ALL
SELECT '2016-11-21' UNION ALL
SELECT '2016-11-19' UNION ALL
SELECT '2016-11-18'
DECLARE #DATE DATE = '2016-11-01'
;WITH CTEYear (_Date) AS
(
SELECT #DATE
UNION ALL
SELECT DATEADD(DAY,1,_Date)
FROM CTEYear
WHERE _Date < EOMONTH(#DATE,0)
)
SELECT * FROM CTEYear
WHERE NOT EXISTS(SELECT 1 FROM #yourTable WHERE _Date = _Values)
OPTION(maxrecursion 0)

Answer 3

You need to generate the dates and then find the missing ones. A recursive CTE is one way to generate a handful of dates. Another way is to use master..spt_values as a list of numbers:
with n as (
select row_number() over (order by (select null)) - 1 as n
from master..spt_values
),
d as (
select dateadd(day, n.n, cast('2016-01-01' as date)) as dte
from n
where n <= 365
)
select d.date
from d left join
#table t
on d.dte = t.date
where t.date is null;
If you are happy enough with ranges of missing dates, you don't need a list of dates at all:
select date, (datediff(day, date, next_date) - 1) as num_missing
from (select t.*, lead(t.date) over (order by t.date) as next_date
from #table t
where t.date >= '2016-01-01'
) t
where next_date <> dateadd(day, 1, date);