Calculate the number of boxes needed for a given set of items (weights) - sql

Question

I have a ms-sql table which looks like this (weight = kg).
I want to be able to calculate number of boxes and weight per box needed for an given identifier. A box can hold up to exactly 30 Kg. All items of that identifier can be mixed within a box. I am limited to sql only (2008) but everything can be used (CTE,Functions,StoredProcs and so on). I tried different approaches (CTE, functions) but i wasn't able to get the right results. any kind of help appreciated.
Expected output
when selecting identifier 100001:
when selecting identifier 100002:
when selecting identifier 100003:
when selecting identifier 100004:
UPDATE
sample table
CREATE TABLE [dbo].[tblTest](
[position] [int] NOT NULL,
[item] [varchar](31) NOT NULL,
[quantity] [money] NOT NULL,
[weight] [money] NOT NULL,
[identifier] [varchar](50) NOT NULL,
CONSTRAINT [PK_tblTest] PRIMARY KEY CLUSTERED
(
[position] ASC,
[identifier] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
sample data
INSERT [dbo].[tblTest] ([position], [item], [quantity], [weight], [identifier]) VALUES (1, N'0000001', 4.0000, 10.0000, N'100001')
INSERT [dbo].[tblTest] ([position], [item], [quantity], [weight], [identifier]) VALUES (1, N'0000003', 3.0000, 15.0000, N'100002')
INSERT [dbo].[tblTest] ([position], [item], [quantity], [weight], [identifier]) VALUES (1, N'0000006', 7.0000, 25.0000, N'100003')
INSERT [dbo].[tblTest] ([position], [item], [quantity], [weight], [identifier]) VALUES (1, N'0000007', 1.0000, 1.5000, N'100004')
INSERT [dbo].[tblTest] ([position], [item], [quantity], [weight], [identifier]) VALUES (1, N'0023021', 2.0000, 14.5000, N'100005')
INSERT [dbo].[tblTest] ([position], [item], [quantity], [weight], [identifier]) VALUES (2, N'0000002', 1.0000, 15.0000, N'100001')
INSERT [dbo].[tblTest] ([position], [item], [quantity], [weight], [identifier]) VALUES (2, N'0000004', 1.0000, 5.0000, N'100002')
INSERT [dbo].[tblTest] ([position], [item], [quantity], [weight], [identifier]) VALUES (2, N'0000008', 1.0000, 2.5000, N'100004')
INSERT [dbo].[tblTest] ([position], [item], [quantity], [weight], [identifier]) VALUES (2, N'0023022', 3.0000, 17.5000, N'100005')
INSERT [dbo].[tblTest] ([position], [item], [quantity], [weight], [identifier]) VALUES (3, N'0000005', 3.0000, 2.5000, N'100002')
INSERT [dbo].[tblTest] ([position], [item], [quantity], [weight], [identifier]) VALUES (3, N'0000009', 3.0000, 6.0000, N'100004')
INSERT [dbo].[tblTest] ([position], [item], [quantity], [weight], [identifier]) VALUES (4, N'0000010', 1.0000, 1.0000, N'100004')

Answer 1

Here is one option:
See the demo here: http://rextester.com/THP2733
setup:
create table tbl
(position integer, item integer, quantity integer, weight decimal(10,2), identifier integer);
insert into tbl
select 1, 1, 4, 10, 100001 union all
select 2, 2, 1, 15, 100001 union all
select 1, 3, 3, 15, 100002 union all
select 2, 4, 1, 5, 100002 union all
select 3, 5, 3, 2.5, 100002 union all
select 1, 6, 7, 25, 100003 union all
select 1, 7, 1, 1.5, 100004 union all
select 2, 8, 1, 2.5, 100004 union all
select 3, 9, 3, 6, 100004 union all
select 4, 10, 1, 1, 100004 ;
query:
with cte(position, item, quantity, weight, identifier, cntr)
as(select position, item, quantity, weight, identifier, quantity
from tbl t1
union all
select t2.position, t2.item, t2.quantity, t2.weight, t2.identifier, cte.cntr - 1
from tbl t2
join cte
on t2.identifier = cte.identifier
and t2.item = cte.item
and cte.cntr > 1
)
select
identifier,
sum(flg) over (partition by identifier order by item, cntr desc) package,
case when rolling_weight - lag(rolling_weight) over (partition by identifier order by cntr desc) is NULL then rolling_weight
else rolling_weight - lag(rolling_weight) over (partition by identifier order by cntr desc)
end weight
from
(
select temp1.*,
case when rolling_weight % 30 = 0 then 1
when rolling_weight = total_weight then 1
when weight + lead(weight) over (partition by identifier order by cntr desc) > 30 then 1
else 0 end as flg
from
(
select
cte.*,
sum(weight) over (partition by identifier order by item, cntr desc) rolling_weight,
sum(weight) over (partition by identifier) total_weight
from cte
) temp1
) temp2
where flg = 1
order by identifier, package