SQL finding Missing Record - sql

Question

I have a scenario where I have to find out missing record.
--Code for Creating Source Table
CREATE TABLE [dbo].[NaTarget](
[BillKey] [int] NULL,
[StartDate] [date] NULL,
[EndDate] [date] NULL
)
GO
--Code for Creating Target Table
CREATE TABLE [dbo].[NaSource](
[BillKey] [int] NULL,
[StartDate] [date] NULL,
[EndDate] [date] NULL
)
GO
--Inserting Records in Source
INSERT INTO [dbo].[NaSource] ([BillKey],[StartDate],[EndDate])
VALUES('1','2014-01-13','2014-03-27')
GO
INSERT INTO [dbo].[NaSource]([BillKey],[StartDate],[EndDate])
VALUES('2','2014-02-14','2014-04-20')
GO
INSERT INTO [dbo].[NaSource]([BillKey],[StartDate],[EndDate])
VALUES('3','2013-11-13','2014-01-18')
GO
--Inserting records In Target
INSERT INTO [dbo].[NaTarget] ([BillKey] ,[StartDate],[EndDate])
VALUES ('1','2014-01-13' , '2014-01-31' )
INSERT INTO [dbo].[NaTarget] ([BillKey] ,[StartDate],[EndDate])
VALUES ('1','2014-02-01' , '2014-02-28' )
INSERT INTO [dbo].[NaTarget] ([BillKey] ,[StartDate],[EndDate])
VALUES ('1','2014-03-01' , '2014-03-27' )
INSERT INTO [dbo].[NaTarget] ([BillKey] ,[StartDate],[EndDate])
VALUES ('2','2014-02-14' , '2014-02-28' )
INSERT INTO [dbo].[NaTarget] ([BillKey] ,[StartDate],[EndDate])
VALUES ('2','2014-03-01' , '2014-03-31' )
INSERT INTO [dbo].[NaTarget] ([BillKey] ,[StartDate],[EndDate])
VALUES ('2','2014-04-01' , '2014-04-20' )
INSERT INTO [dbo].[NaTarget] ([BillKey] ,[StartDate],[EndDate])
VALUES ('3','2013-11-13' , '2013-11-30' )
INSERT INTO [dbo].[NaTarget] ([BillKey] ,[StartDate],[EndDate])
VALUES ('3','2013-12-01' , '2013-12-31' )
INSERT INTO [dbo].[NaTarget] ([BillKey] ,[StartDate],[EndDate])
VALUES ('3','2014-01-01' , '2014-01-18' )
Now for any BillKey, StartDate in target will be StartDate from Source and EndDate will be last date of month and now for same Billkey, next record will have 1st date of next month and EndDate will be last date, until last date of same BillKey is reached.
I have to find any record if it gets deleted.
Example if BillKey = 3
StartDate= 2013-12-01 EndDate = 2013-12-31 is
not present in target we need to find it
Example will explain it better

Answer 1

Here is an attempt at this: If I understand your question correctly, you're looking to check to see if any expected values in the Target table based on the Start and End Dates in the Source table aren't actually there.
You'll need to essentially recreate the results table with what you are expecting from the NaSource table's StartDate and EndDate, and check that against the NaTarget table.
I'm positive there's a more efficient way of doing this (preferably without using cursors and while loops), but this should give you the results you're looking for:
Declare #Results Table
(
BillKey Int,
StartDate Date,
EndDate Date
)
Declare #BillKey Int
Declare #EndDate Date
Declare #Cur Date
Declare cur Cursor Fast_Forward For
Select BillKey, StartDate, EndDate
From NaSource
Open cur
While 1 = 1
Begin
Fetch Next From cur Into #BillKey, #Cur, #EndDate
If ##FETCH_STATUS <> 0 Break
While (#Cur < #EndDate)
Begin
Insert #Results
Select #BillKey, #Cur,
Case When DATEADD(d, -1, DATEADD(m, DATEDIFF(m, 0, #Cur) + 1, 0)) > #EndDate
Then Convert(Date, #EndDate)
Else Convert(Date, DATEADD(d, -1, DATEADD(m, DATEDIFF(m, 0, #Cur) + 1, 0)))
End As EndDate
Set #Cur = DATEADD(m, DATEDIFF(m, -1, #Cur), 0)
End
End
Close cur
Deallocate cur
Select R.*
From #Results R
Where Not Exists
(
Select 1
From NaTarget T
Where R.BillKey = T.BillKey
And R.StartDate = T.StartDate
And R.EndDate = T.EndDate
)

Answer 2

Here's my solution using recursive CTE. Build what the natarget table should look like and compare it to the actual natarget. I started getting confused on the dates piece so it may be simplified but this does work.
;with targetCte
as
(
select billkey,
startdate,
CAST(DATEADD(d, -1, DATEADD(m, DATEDIFF(m, 0, startdate) + 1, 0)) as DATE) as enddate
from nasource
union all
select t.billkey,
cast(DATEADD(month, DATEDIFF(mm, 0, dateadd(mm, 1, t.startdate)), 0) as DATE) ,
case
when cast(DATEADD(d, -1, DATEADD(m, DATEDIFF(m, 0, DATEADD(month, DATEDIFF(mm, 0, dateadd(mm, 1, t.startdate)), 0)) + 1, 0)) as DATE) < n.enddate then cast(DATEADD(d, -1, DATEADD(m, DATEDIFF(m, 0, DATEADD(month, DATEDIFF(mm, 0, dateadd(mm, 1, t.startdate)), 0)) + 1, 0)) as DATE)
else n.enddate
end
as enddate
from targetCte t
join nasource n on n.billkey = t.billkey
where t.enddate < n.enddate
)
select * from targetcte t
where not exists
(select *
from natarget nt
where t.billkey = nt.billkey
and t.startdate = nt.startdate
and t.enddate = nt.enddate)

Answer 3

Insert all records into one table with a unique ID (call this main table)
Take the table with deleted records then run a SELECT * on the Main table where ID NOT IN ID column of the deleted records table

Answer 4

It's filtering by reconciliation. LEFT Join both tables on StartDate AND EndDate pairs WHERE RIGHT keys are NULL. Google SQL Joins and you can find a very useful diagram on issues like that.