Adjust values of individual rows based upon order then roll up - sql

Question

OK - Let me explain this. I have a series of rows - the rows have a "weight" value and a "qty" and "rate" - others but am concerned with these for now...
What I need to do is to split the rows - which I have done in the below, based on the qty - so for a row that has a qty > 1 - a row is replicated for each qty value.
So, with them all split now - I need to determine which has the highest "weight" - then I need to keep that rate at 100%. All others will be rate/2.
Then - lastly - I need to roll the rows back up - so all like IDs are collapsed with aggregated rates - so back to single rows with sumed rates
/*
--create numbers table if don't already have one...
select top 1000000 row_number() over(order by t1.number) as N
into dbo.Numbers
from master..spt_values t1
cross join master..spt_values t2
*/
DECLARE #table TABLE
(
id int IDENTITY(1,1) ,
code varchar(10) ,
codeStatus varchar ,
qty int ,
rate money ,
codeWeight float ,
comment varchar(100)
)
INSERT INTO #table SELECT '12345' , 'T' , 3 , 375.86 , 5.6589 , NULL
INSERT INTO #table SELECT '45678' , 'T' , 2 , 2 , 4.0000 , NULL
INSERT INTO #table SELECT '11223' , 'T' , 1 , 2 , 3.0000 , NULL
SELECT t.id ,
t.code ,
t.qty ,
t.rate ,
t.codeWeight ,
n.N
FROM #table t
JOIN dbo.Numbers n on n.N <= t.qty
ORDER BY id ,
N

Answer 1

Here's a way to do the break down without needing the numbers table:
http://sqlfiddle.com/#!6/93b09/1
with cte as
(
SELECT id, code, qty, rate, codeWeight, qty N
FROM myTable t
union all
select id, code, qty, rate, codeWeight, N - 1
from cte
where N > 1
)
SELECT id, code, qty, rate, codeWeight, N
FROM cte
ORDER BY id, N
If I've understood the next steps correctly, then this should do what you're after...
http://sqlfiddle.com/#!6/93b09/4
declare #temp table(id int, code varchar(10), qty int, rate money, codeWeight float, N int)
;with cte as
(
SELECT id, code, qty, rate, codeWeight, qty N
FROM myTable t
union all
select id, code, qty, rate, codeWeight, N - 1
from cte
where N > 1
)
insert #temp
SELECT id, code, qty, rate, codeWeight, N
FROM cte
ORDER BY id, N
update t
set rate = t.rate / 2.0
from #temp t
inner join myTable m on m.id = t.id
and t.qty < m.qty
select id, code, max(qty) qty, sum(rate) rate, codeWeight
from #temp
group by id, code, codeWeight
Update
Based on discussion in comments, this SQL should do everything you need:
http://sqlfiddle.com/#!6/93b09/13
select id
, code
, codeStatus
, qty
, case (row_number() over (order by codeWeight desc))
when 1 then rate + case when qty > 0 then qty-1 else 0 end * rate / 2.0
else qty * rate / 2.0
end rate
, codeWeight
, comment
from myTable
i.e. the item with the greatest weight value returns a rate made up of one unit at the full rate, plus the remaining units at half price.
All other items are given rates which are their full quantity at half price.