Identify full vs half yearly datasets in SQL - sql

Question

I have a table with two fields of interest for this particular exercise: a CHAR(3) ID and a DATETIME. The ID identifies the submitter of the data - several thousand rows. The DATETIME is not necessarily unique, either. (The primary keys are other fields of the table.)
Data for this table is submitted every six months. In December, we receive July-December data from each submitter, and in June we receive July-June data. My task is to write a script that identifies people who have only submitted half their data, or only submitted January-June data in June.
...Does anyone have a solution?

Answer 1

For interest, this is what I wound up using. It was based off Stephen's answer, but with a few adaptations.
It's part of a larger script that's run every six months, but we're only checking this every twelve months - hence the "If FullYear = 1". I'm sure there's a more stylish way to identify the boundary dates, but this seems to work.
IF #FullYear = 1
BEGIN
DECLARE #FirstDate AS DATETIME
DECLARE #LastDayFirstYear AS DATETIME
DECLARE #SecondYear AS INT
DECLARE #NewYearsDay AS DATETIME
DECLARE #LastDate AS DATETIME
SELECT #FirstDate = MIN(dscdate), #LastDate = MAX(dscdate)
FROM TheTable
SELECT #SecondYear = DATEPART(yyyy, #FirstDate) + 1
SELECT #NewYearsDay = CAST(CAST(#SecondYear AS VARCHAR)
+ '-01-01' AS DATETIME)
INSERT INTO #AuditResults
SELECT DISTINCT
'Submitter missing Jan-Jun data', t.id
FROM TheTable t
WHERE
EXISTS (
SELECT 1
FROM TheTable t1
WHERE t.id = t1.id
AND t1.date >= #FirstDate
AND t1.date < #NewYearsDay )
AND NOT EXISTS (
SELECT 1
FROM TheTable t2
WHERE t2.date >= #NewYearsDay
AND t2.date <= #LastDate
AND t2.id = t.id
GROUP BY t2.id )
GROUP BY t.id
END

Answer 2

From your description, I wouldn't worry about the efficiency of the query since apparently it only needs to run twice a year!
There are a few ways to do this, which one is 'best' depends on the data that you have. The datediff (on max/min date values) you suggested should work, another option is to just count records for each submitted within each date range, e.g.
select * from (
select T.submitterId,
(select count(*)
from TABLE T1
where T1.datefield between [july] and [december]
and T1.submitterId = T.submitterId
group by T1.submitterId) as JDCount,
(select count(*)
from TABLE T2
where T2.datefield between [december] and [june]
and T2.submitterId = T.submitterId
group by T2.submitterId) as DJCount
from TABLE T) X
where X.JDCount <= 0 OR X.DJCount <= 0
Caveat: untested query off the top of my head; your mileage may vary.

Answer 3

I later realised that I was supposed to check to make sure that there was data for both July to December and January to June. So this is what I wound up in v2:
SELECT #avgmonths = AVG(x.[count])
FROM ( SELECT CAST(COUNT(DISTINCT DATEPART(month,
DATEADD(month,
DATEDIFF(month, 0, dscdate),
0))) AS FLOAT) AS [count]
FROM HospDscDate
GROUP BY hosp
) x
IF #avgmonths > 7
SET #months = 12
ELSE
SET #months = 6
SELECT 'Submitter missing data for some months' AS [WarningType],
t.id
FROM TheTable t
WHERE EXISTS ( SELECT 1
FROM TheTable t1
WHERE t.id = t1.id
HAVING COUNT(DISTINCT DATEPART(month,
DATEADD(month, DATEDIFF(month, 0, t1.Date), 0))) < #months )
GROUP BY t.id