Summing row before in a condition (SQL) - sql

Question

I have a spreadsheet where sales data is interspersed with other data in columns. The column headings for S always end with the sum between I(row before)+P(current row) - I(Current row). I would like the data to sum for each row only. I need to do this with SQL queries.
for example :
if the week is 201520, it will return 'X',
but if it isn't week 201520, then S(Column) = I(week 201547) + P(week 201548) - I(Week 201548)
Currently my queries is like this, but I don't get the logic in query for this case, can anybody help me?
select c.[SHIP TO CODE],Area,[Dealer/Account],
c.[PRODUCT CODE],c.Model,c.Category,c.WEEK,c.I,c.P,c.S
from(select distinct b.[SHIP TO CODE],rp.Model,rp.Category,b.[PRODUCT CODE],b.WEEK,b.QTY,
case when TYPE = 'I' then 'I' end as I,
case when TYPE = 'P' then 'P' end as P,
case when WEEK = '201550' then 'X' end as S from
(
select [SHIP TO CODE],[PRODUCT CODE],WEEK,qty,TYPE from Rekap
a
union
select [Ship-to party],Material,[Week-Ok],[1st G/I Qty],category from
SOT left join
SDate on [Tgl SAP] = [1st G/I Date]
)b
left join [Ref Prod]rp
on b.[PRODUCT CODE] = rp.ProductID
where WEEK is not null
)
c
left join [Ref Dealer]rd
on c.[SHIP TO CODE] = rd.[Ship To Code]
order by [Ship To Code],WEEK ASC

Answer 1

select * into #a from (
select
case when abcd.WEEK = '201520' then 'X' end as S,*
from(select abc.Area,abc.Channel,abc.[Dealer/Account],abc.[PRODUCT CODE],rp.Model,rp.Category,abc.week,abc.I,abc.P
from (select ab.[SHIP TO CODE],rd.Area,rd.Channel,rd.[Dealer/Account],ab.[PRODUCT CODE],
ab.WEEK,case when TYPE = 'I' then isnull(QTY,0) end as I,
case when TYPE = 'P' then isnull(qty,0) end as P
from(
select [SHIP TO CODE],[PRODUCT CODE],WEEK,qty,TYPE from Rekap
a
union all
select [Ship-to party],Material,[Week-Ok],[1st G/I Qty],category from
SOT left join
SDate on [Tgl SAP] = [Billing Date])
ab
left join [Ref Dealer]rd
on ab.[SHIP TO CODE] = rd.[Ship To Code]
)abc
left join
[Ref Prod]rp on rp.ProductID = abc.[PRODUCT CODE]
)abcd
--order by abcd.[Dealer/Account],abcd.WEEK
) a
select Area, Channel, [Dealer/Account], [Product Code], model, category, week,
CASE WHEN I IS NULL THEN 'P' WHEN P IS NULL THEN 'I' END type,
SUM(ISNULL(I,0)+ISNULL(p,0)) amount
into #b
from #a
where week is not null
group by area, channel,[dealer/account], [product code], model, category, week,
CASE WHEN I IS NULL THEN 'P' WHEN P IS NULL THEN 'I' END
order by week
--Grouping all, put into temp table
select Area, Channel, [Dealer/Account], [Product Code], model, category, week,
SUM(ISNULL(I,0)) I, SUM(ISNULL(p,0)) p
into #c
from #a
where week is not null
group by area, channel,[dealer/account], [product code], model, category, week
order by week
select *,(select MAX(week) from #c where a.week>#c.week
--IF NOT NEEDED
--and
--a.area=#c.area and a.channel=#c.channel and a.[dealer/account]=#c.[dealer/account] and a.[product code]=#c.[product code]
--and a.model=#c.model and a.category=#c.category
-- END OF
) lastweek
into #d
from #c a
select a.*, a.P-a.I+b.I s from #d a left join #d b on
a.area=b.area and a.channel=b.channel and a.[dealer/account]=b.[dealer/account] and a.[product code]=b.[product code]
and a.model=b.model and a.category=b.category and
a.lastweek=b.week
order by area, channel,[dealer/account], [product code], model, category, week