How can I consolidate this code to avoid multiple #temp table writes? - tsql

Question

Although this code is working, it isn't very efficient--making heavy use of temp tables, which I'd rather consolidate. The create sumtest table and the insert statements that write to it are included for anyone interested in working with the sample data.
CREATE TABLE SumTest(
POSDate datetime NULL,
debit money NULL,
credit money NULL,
RollingBalance money NULL,
expires datetime NULL,
ExpiringDebitBalance_2013 money,
ExpiringDebitBalance_2014 money
);
-- mimic actual sales transactions
insert into sumtest (POSDate,debit,credit,expires) values ('Jan 5 2013 12:00AM','670.00','22.00','Dec 31 2014 12:00AM');
insert into sumtest (POSDate,debit,credit,expires) values ('Jan 6 2013 12:00AM','821.00','0.00','Dec 31 2014 12:00AM');
insert into sumtest (POSDate,debit,credit,expires) values ('Mar 8 2013 12:00AM','62.00','700.00','Dec 31 2014 12:00AM');
insert into sumtest (POSDate,debit,credit,expires) values ('Mar 11 2013 12:00AM','78.00','29.00','Dec 31 2014 12:00AM');
insert into sumtest (POSDate,debit,credit,expires) values ('Mar 11 2013 12:00AM','900.00','87.00','Dec 31 2014 12:00AM');
insert into sumtest (POSDate,debit,credit,expires) values ('Apr 16 2013 12:00AM','0.00','440.00',NULL);
insert into sumtest (POSDate,debit,credit,expires) values ('Aug 18 2013 12:00AM','0.00','50.00',NULL);
insert into sumtest (POSDate,debit,credit,expires) values ('Aug 19 2013 12:00AM','470.00','200.00','Dec 31 2014 12:00AM');
insert into sumtest (POSDate,debit,credit,expires) values ('Dec 31 2012 12:00AM','1000.00','200.00','Dec 31 2013 12:00AM');
insert into sumtest (POSDate,debit,credit,expires) values ('Dec 22 2013 12:00AM','200.00','0.00','Dec 31 2014 12:00AM');
insert into sumtest (POSDate,debit,credit,expires) values ('Dec 20 2013 12:00AM','500.00','0.00','Dec 31 2014 12:00AM');
insert into sumtest (POSDate,debit,credit,expires) values ('Nov 10 2012 12:00AM','200.00','0.00','Dec 31 2013 12:00AM');
insert into sumtest (POSDate,debit,credit,expires) values ('Nov 11 2012 12:00AM','150.00','0.00','Dec 31 2013 12:00AM');
insert into sumtest (POSDate,debit,credit,expires) values ('Nov 15 2012 12:00AM','0.00','100.00',NULL);
-- // ---------- REAL CODE BEGINS -------------------------- // --
create table #work
(
POSYear int NULL,
POSMonth int NULL,
debit money NULL,
credit money NULL,
RollingBalance money NULL,
expires datetime
)
-- start with ditching the time
insert into #work
(POSYear,POSMonth,debit,credit,expires)
select datepart(Year, POSDate) as POSYear
,datepart(Month, POSDate) as POSMonth
,debit
,credit
,expires
from sumtest
-- dump an ordered set by year,month with a rolling balance of all points/redemptions
;with distilled as
(select POSYear,
POSMonth,
TotalDebit = sum(debit),
TotalCredit = sum(credit),
expires
from #work
group by POSYear,POSMonth,expires
)
select POSYear,
POSMonth,
TotalDebit,
TotalCredit,
RollingBalance = sum(totaldebit + (totalcredit)*-1) over ( order by POSYear, POSMonth),
expires
into #work2
from distilled
order by POSYear,POSMonth,TotalDebit,TotalCredit
-- filter out credits lines that dont have an expiration date
-- Note: I would rather not do this--if there is a better way
-- to sum up by yyyy,mm here to consolidate to
-- single rows please advise.
select x.POSYear,
x.POSMonth,
sum(x.TotalDebit) as TotalDebit,
sum(x.TotalCredit) as TotalCredit,
x.RollingBalance,
EXPYear = datepart(Year, y.expires),
EXPMonth = datepart(Month, y.expires)
into #work3
from #work2 x
inner join #work2 y on x.posyear = y.posyear
and x.posmonth = y.posmonth
where y.expires is not null
group by x.posyear,x.posmonth,x.rollingbalance,y.expires
order by posyear,posmonth
-- add back in lines that are single credits, w/o debits
-- Note: I like this even less! :-\
INSERT INTO #work3
(POSYear,POSMonth,TotalDebit,TotalCredit,RollingBalance,EXPYear,EXPMonth)
select
POSYear,
POSMonth,
TotalDebit,
TotalCredit,
RollingBalance,
case
when expires is null then (POSYear + 1)
end as EXPYear,
case
when expires is null then 12
end as EXPMonth
from #work2
where (POSYear + POSMonth) NOT IN (
select POSYear + POSMonth
from #work3);

Answer 1

There doesn't appear to be a need for #work which can be replaced with
;with distilled as
(
select POSYear,
POSMonth,
TotalDebit = sum(debit),
TotalCredit = sum(credit),
expires
from (
select datepart(Year, POSDate) as POSYear
,datepart(Month, POSDate) as POSMonth
,debit
,credit
,expires
from sumtest
)
group by POSYear,POSMonth,expires
)
select POSYear,
POSMonth,
TotalDebit,
TotalCredit,
RollingBalance = sum(totaldebit + (totalcredit)*-1) over ( order by POSYear, POSMonth),
expires
into #work2
from distilled
I think the last two queries can be simplified to
select x.POSYear,
x.POSMonth,
sum(case when expires is null then 0 else x.TotalDebit end) as TotalDebit,
sum(case when expires is null then 0 else x.TotalCredit end) as TotalCredit,
x.RollingBalance,
EXPYear = case when expires is null then (POSYear + 1)
else datepart(Year, y.expires)
end,
EXPMonth = case when expires is null then 12
else datepart(Month, y.expires)
end
into #work3
from #work2 x
inner join #work2 y on x.posyear = y.posyear
and x.posmonth = y.posmonth
group by x.posyear,x.posmonth,x.rollingbalance,y.expires
You also don't seem to really need to be ordering anything

Answer 2

OK, here's the refined version--no temp tables.
SELECT
POSYear
, POSMonth
, TotalDebit AS TotalEarned
, TotalCredit AS TotalRedeemed
, RollingBalance
, EXPYear
, EXPMonth
, case
when EXPYear = 2013 then RollingBalance
else 0
end as EXPRollingBal_2013
, case
when prevEXPYear <> EXPYear then lag(RollingBalance,1) over (ORDER BY POSYear ,POSMonth) - TotalCredit
end as "EXPCarryForwardBal" -- // Note: This only works for the first instance AFTER then new year. Wrong!
, case
-- when EXPYear = 2014 then RollingBalance // Note: This is WRONG, zero it out for now.
when EXPYear = 2014 then 0.00
else 0
end as EXPRollingBal_2014
INTO #baseExpiring
FROM (
SELECT
POSYear
, POSMonth
, TotalDebit
, TotalCredit
, sum(TotalDebit - TotalCredit) over (ORDER BY POSYear ,POSMonth) AS RollingBalance
, EXPYear
, EXPMonth
, lag(EXPYear,1) over (ORDER BY POSYear ,POSMonth) as prevEXPYear
FROM (
SELECT
year(posdate) AS POSYear
, month(posdate) AS POSMonth
, sum(debit) AS TotalDebit
, sum(credit) AS TotalCredit
, CASE
WHEN expires IS NULL THEN year(posdate) + 1
ELSE year(expires)
END AS EXPYear
, CASE
WHEN expires IS NULL THEN 12
ELSE month(expires)
END AS EXPMonth
FROM SumTest
GROUP BY
year(posdate)
, month(posdate)
, CASE
WHEN expires IS NULL THEN year(posdate) + 1
ELSE year(expires)
END
, CASE WHEN expires IS NULL THEN 12
ELSE month(expires)
END
) as dataset1 -- // resolve line consolidation when there's a standalone redempton when summed, leaving 2 distinct yyyy,mm rows.
) as dataset2 -- // broader resolution of rolling balance w/windowing.
;