distribute value to all rows while updating table - sql

Question

I have table structure like tblCustData
ID UserID Fee FeePaid
1 12 150 0
2 12 100 0
3 12 50 0
And value to be update in FeePaid Column such that if i have value in #Amt variable in 200 Then it should update any two rows
Output should be like
ID UserID Fee FeePaid
1 12 150 150
2 12 100 50
3 12 50 0
FeePaid should not be grater than Fee Column But if i pass 350 in #Amt variable it should produce output like
ID UserID Fee FeePaid
1 12 150 200
2 12 100 100
3 12 50 50
Only if #Amt is exceeding the total value in Fee column
I can not think beyond this query
Update tblCustData
Set FeePaid=#Amt
Where UserID=12

Answer 1

First with CTE syntax we prepare a table with sums distribution and then using unique field Code update the main table using CASE to handle all possible ways (including first row with remainder).
Declare #Amt int;
SET #Amt=250;
with T as
(
SELECT ROW_NUMBER() OVER (ORDER BY Fee desc) as rn, *
FROM tblCustData WHERE UserId=12
)
,T2 as
(
SELECT *,
ISNULL((SELECT SUM(Fee-FeePaid) FROM T WHERE T1.RN<RN),0) as PrevSum
FROM T as T1
)
UPDATE
A
SET A.FeePaid = A.FeePaid+ CASE WHEN (B.PrevSum+B.Fee-B.FeePaid<=#Amt)
AND (B.RN<>1)
THEN B.Fee-B.FeePaid
WHEN (B.PrevSum+B.Fee-B.FeePaid<=#Amt) AND (B.RN=1)
THEN #Amt-B.PrevSum
WHEN B.PrevSum>=#Amt
THEN 0
WHEN B.PrevSum+B.Fee-B.FeePaid>#Amt
THEN #Amt-B.PrevSum
END
FROM
tblCustData A
JOIN T2 B ON A.Code = B.Code
GO
SQLFiddle demo

Answer 2

Try ..
declare #t table (id int identity, UserId int, Fee money, FeePaid money)
insert into #t (UserID, Fee, FeePaid)
values
(12, 150, 0)
,(12, 100, 0)
,(12, 50 , 0)
declare #amt money = 200; -- change to 400 to test over paid
declare #Fees money;
select #Fees = sum(Fee) from #t;
declare #derivedt table (deid int, id int, UserId int, Fee money, FeePaid money)
insert into #derivedt (deid, id, UserId, Fee, FeePaid)
select row_number() over (order by case when #amt <= #Fees then id else -id end asc), id, UserId, Fee, FeePaid
from #t
-- order by case when #amt <= #Fees then id else -id end asc
; with cte(deid, id, UserId, Fee, FeePaid, Remainder)
as
(
select 0 as deid, 0 as id, 0 as UserId, cast(0.00 as money) as Fee, cast(0.00 as money) as FeePaid , #Amt as Remainder
from #derivedt
where id = 1
union all
select t.deid, t.id, t.UserId, t.Fee, case when cte.Remainder > t.Fee then t.Fee else cte.Remainder end as FeePaid
, case when cte.Remainder > t.Fee then cte.Remainder - t.Fee else 0 end as Remainder
from #derivedt t inner join cte cte on t.deid = (cte.deid + 1)
)
update origt
set FeePaid = det.FeePaid
from #t origt
inner join
(
select cte1.deid, cte1.id, cte1.UserId, cte1.Fee, cte1.FeePaid + ISNULL(cte2.Remainder, 0) as FeePaid
from cte cte1
left outer join (select top 1 deid, Remainder from cte order by deid desc) cte2
on cte1.deid = cte2.deid
where cte1.deid > 0
) det
on origt.id = det.id
select *
from #t
Modified to continuous update of value..
-- Create table once and insert into table once
create table #t (id int identity, UserId int, Fee money, FeePaid money)
insert into #t (UserID, Fee, FeePaid)
values
(12, 150, 0)
,(12, 100, 0)
,(12, 50 , 0)
-- ===============================
-- Run multiple times to populate #t table
declare #amt money = 100; -- change to 400 to test over paid
declare #Fees money;
select #Fees = sum(Fee - FeePaid) from #t;
declare #derivedt table (deid int, id int, UserId int, Fee money, FeePaid money)
insert into #derivedt (deid, id, UserId, Fee, FeePaid)
select row_number() over (order by case when #amt <= #Fees then id else -id end asc), id, UserId, (Fee - FeePaid) as Fee, FeePaid
from #t
-- order by case when #amt <= #Fees then id else -id end asc
; with cte(deid, id, UserId, Fee, FeePaid, Remainder)
as
(
select 0 as deid, 0 as id, 0 as UserId, cast(0.00 as money) as Fee, cast(0.00 as money) as FeePaid , #Amt as Remainder
from #derivedt
where id = 1
union all
select t.deid, t.id, t.UserId, t.Fee, case when cte.Remainder >= t.Fee then t.Fee else cte.Remainder end as FeePaid
, case when cte.Remainder >= t.Fee then cte.Remainder - t.Fee else 0 end as Remainder
from #derivedt t inner join cte cte on t.deid = (cte.deid + 1)
)
update origt
set FeePaid = origt.FeePaid + det.FeePaid
from #t origt
inner join
(
select cte1.deid, cte1.id, cte1.UserId, cte1.Fee, cte1.FeePaid + ISNULL(cte2.Remainder, 0) as FeePaid, cte1.Remainder
from cte cte1
left outer join (select top 1 deid, Remainder from cte order by deid desc) cte2
on cte1.deid = cte2.deid
where cte1.deid > 0
) det
on origt.id = det.id
select *
from #t
-- Drop temp table after
-- drop table #t

Answer 3

Apart from your code, I added an identity column to your table. See the code.
DECLARE #TAB TABLE(ID INT IDENTITY(1,1),USERID INT, FEE INT, FEEPAID INT)
INSERT INTO #TAB VALUES (12,150,0),(12,100,0),(12,50,0)
DECLARE #AMOUNT INT = 230,
#AMOUNTNEW INT = 0,
#B INT = 1,
#S INT = 1,#E INT = (SELECT COUNT(*) FROM #TAB)
WHILE #S <= #E
BEGIN
UPDATE LU
SET LU.FEEPAID = CASE WHEN #AMOUNT >= FEE THEN FEE ELSE #AMOUNT END
FROM #TAB LU
WHERE LU.ID = #S
SET #AMOUNT = #AMOUNT - (SELECT FEE FROM #TAB WHERE ID = #S)
IF #AMOUNT <= 0
SET #S = #E
SET #S = #S + 1
END
SELECT * FROM #TAB
Result:
I hope the idea is clear, we can work from here.