T-SQL: Combining rows based on another table - tsql

Question

I am seeking to alter a table content based on information of another table using a stored procedure. To make my point (and dodge my rusty English skills) I created the following simplification.
I have a table with fragment amounts of the form
SELECT * FROM [dbo].[obtained_fragments] ->
fragment amount
22 42
76 7
101 31
128 4
177 22
212 6
and a table that lists all possible combinations to combine these fragments to other fragments.
SELECT * FROM [dbo].[possible_combinations] ->
fragment consists_of_f1 f1_amount_needed consists_of_f2 f2_amount_needed
1001 128 1 22 3
1004 151 1 101 12
1012 128 1 177 6
1047 212 1 76 4
My aim is to alter the first table so that all possible fragment combinations are performed, leading to
SELECT * FROM [dbo].[obtained_fragments] ->
fragment amount
22 30
76 3
101 31
177 22
212 5
1001 4
1047 1
In words, combined fragments are added to the table based on [dbo].[possible_combinations], and the amount of needed fragments is reduced. Depleted fragments are removed from the table.
How do I achieve this fragment transformation in an easy way? I started writing a while loop, checking if sufficient fragments are available, inside of a for loop, interating through the fragment numbers. However, I am unable to come up with a functional amount check and begin to wonder if this is even possible in T-SQL this way.
The code doesn't have to be super efficient since both tables will always be smaller than 200 rows.
It is important to note that it doesn't matter which combinations are created.
It might come in handy that [f1_amount_needed] always has a value of 1.
UPDATE
Using the solution of iamdave, which works perfectly fine as long I don't touch it, I receive the following error message:
Column name or number of supplied values does not match table definition.
I barely changed anything really. Is there a chance that using existing tables with more than the necessary columns instead of declaring the tables (as iamdave did) makes this difference?
DECLARE #t TABLE(Binding_ID int, Exists_of_Binding_ID_2 int, Exists_of_Pieces_2 int, Binding1 int, Binding2 int);
WHILE 1=1
BEGIN
DELETE #t
INSERT INTO #t
SELECT TOP 1
k.Binding_ID
,k.Exists_of_Binding_ID_2
,k.Exists_of_Pieces_2
,g1.mat_Binding_ID AS Binding1
,g2.mat_Binding_ID AS Binding2
FROM [dbo].[vwCombiBinding] AS k
JOIN [leer].[sandbox5] AS g1
ON k.Exists_of_Binding_ID_1 = g1.mat_Binding_ID AND g1.Amount >= 1
JOIN [leer].[sandbox5] AS g2
ON k.Exists_of_Binding_ID_2 = g2.mat_Binding_ID AND g2.Amount >= k.Exists_of_Pieces_2
ORDER BY k.Binding_ID
IF (SELECT COUNT(1) FROM #t) = 1
BEGIN
UPDATE g
SET Amount = g.Amount +1
FROM [leer].[sandbox5] AS g
JOIN #t AS t
ON g.mat_Binding_ID = t.Binding_ID
INSERT INTO [leer].[sandbox5]
SELECT
t.Binding_ID
,1
FROM #t AS t
WHERE NOT EXISTS (SELECT NULL FROM [leer].[sandbox5] AS g WHERE g.mat_Binding_ID = t.Binding_ID);
UPDATE g
SET Amount = g.Amount - 1
FROM [leer].[sandbox5] AS g
JOIN #t AS t
ON g.mat_Binding_ID = t.Binding1
UPDATE g
SET Amount = g.Amount - t.Exists_of_Pieces_2
FROM [leer].[sandbox5] AS g
JOIN #t AS t
ON g.mat_Binding_ID = t.Binding2
END
ELSE
BREAK
END
SELECT * FROM [leer].[sandbox5]

Answer 1

You can do this with a while loop that contains several statements to handle your iterative data updates. As you need to make changes based on a re-assessment of your data each iteration this has to be done in a loop of some kind:
declare #f table(fragment int,amount int);
insert into #f values (22 ,42),(76 ,7 ),(101,31),(128,4 ),(177,22),(212,6 );
declare #c table(fragment int,consists_of_f1 int,f1_amount_needed int,consists_of_f2 int,f2_amount_needed int);
insert into #c values (1001,128,1,22,3),(1004,151,1,101,12),(1012,128,1,177,6),(1047,212,1,76,4);
declare #t table(fragment int,consists_of_f2 int,f2_amount_needed int,fragment1 int,fragment2 int);
while 1 = 1
begin
-- Clear out staging area
delete #t;
-- Populate with the latest possible combination
insert into #t
select top 1 c.fragment
,c.consists_of_f2
,c.f2_amount_needed
,f1.fragment as fragment1
,f2.fragment as fragment2
from #c as c
join #f as f1
on c.consists_of_f1 = f1.fragment
and f1.amount >= 1
join #f as f2
on c.consists_of_f2 = f2.fragment
and f2.amount >= c.f2_amount_needed
order by c.fragment;
-- Update fragments table if a new combination can be made
if (select count(1) from #t) = 1
begin
-- Update if additional fragment
update f
set amount = f.amount + 1
from #f as f
join #t as t
on f.fragment = t.fragment;
-- Insert if a new fragment
insert into #f
select t.fragment
,1
from #t as t
where not exists(select null
from #f as f
where f.fragment = t.fragment
);
-- Update fragment1 amounts
update f
set amount = f.amount - 1
from #f as f
join #t as t
on f.fragment = t.fragment1;
-- Update fragment2 amounts
update f
set amount = f.amount - t.f2_amount_needed
from #f as f
join #t as t
on f.fragment = t.fragment2;
end
else -- If no new combinations possible, break the loop
break
end;
select *
from #f;
Output:
+----------+--------+
| fragment | amount |
+----------+--------+
| 22 | 30 |
| 76 | 3 |
| 101 | 31 |
| 128 | 0 |
| 177 | 22 |
| 212 | 5 |
| 1001 | 4 |
| 1047 | 1 |
+----------+--------+