Create "Sets" within the same table based on multi-column criteria - sql-server

Question

For every unique combination of BoxId and Revision with a single UnitTypeId of 1 and a single UnitTypeId of 2 both having a NULL SetNumber, assign a SetNumber of 1.
Table and data setup:
IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[UnitTypes]') AND type in (N'U'))
Drop Table dbo.UnitTypes
IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[Tracking]') AND type in (N'U'))
DROP TABLE [dbo].[Tracking]
GO
CREATE TABLE dbo.UnitTypes
(
Id int NOT NULL,
Notes varchar(80)
)
GO
CREATE TABLE dbo.Tracking
(
Id int NOT NULL IDENTITY (1, 1),
BoxId int NOT NULL,
Revision int NOT NULL,
UnitValue int NULL,
UnitTypeId int NULL,
SetNumber int NULL
)
GO
ALTER TABLE dbo.Tracking ADD CONSTRAINT
PK_Tracking PRIMARY KEY CLUSTERED
(
Id
)
GO
Insert Into dbo.UnitTypes (Id, Notes) Values (1, 'X Coord'),
(2, 'Y Coord'),
(3, 'Weight'),
(4, 'Length')
Go
Insert Into dbo.Tracking (BoxId, Revision, UnitValue, UnitTypeId, SetNumber)
Values (1165, 1, 150, 1, NULL),
(1165, 1, 1477, 2, NULL),
(1165, 1, 31, 4, NULL),
(1166, 1, 425, 1, 1),
(1166, 1, 1146, 2, 1),
(1166, 1, 438, 1, NULL),
(1166, 1, 1163, 2, NULL),
(1167, 1, 560, 1, NULL),
(1167, 1, 909, 2, NULL),
(1167, 1, 12763, 3, NULL),
(1168, 1, 21, 1, NULL),
(1168, 1, 13109, 3, NULL)
The ideal results would be:
Id BoxId Revision UnitValue UnitTypeId SetNumber
1 1165 1 150 1 1
2 1165 1 1477 2 1
3 1165 1 31 4 1
4 1166 1 425 1 1
5 1166 1 1146 2 1
6 1166 1 438 1 NULL <--NULL Because there is already an existing Set
7 1166 1 1163 2 NULL <--NULL Because there is already an existing Set
8 1167 1 560 1 1
9 1167 1 909 2 1
10 1167 1 12763 3 1
11 1168 1 21 1 NULL <--NULL Because there is not exactly one UnitTypeId of 1 and exactly one UnitTypeId of 2 for this BoxId\Revision combination.
12 1168 1 13109 3 NULL <--NULL Because there is not exactly one UnitTypeId of 1 and exactly one UnitTypeId of 2 for this BoxId\Revision combination.
EDIT:
The question is how can I update the SetNumber, given the constraints above, using pure TSQL?

Answer 1

If I understand your question correctly, you could do this with a subquery that demands all conditions are met:
update t1
set SetNumber = 1
from dbo.Tracking t1
where SetNumber is null
and 1 =
(
select case
when count(case when t2.UnitTypeId = 1 then 1 end) <> 1 then 0
when count(case when t2.UnitTypeId = 2 then 1 end) <> 1 then 0
when count(t2.SetNumber) <> 0 then 0
else 1
end
from dbo.Tracking t2
where t1.BoxId = t2.BoxId
and t1.Revision = t2.Revision
)
The count(t2.SetNumber) is a bit tricky: this will only count rows where SetNumber is not null. So this meets the criterion that no other set with the same (BoxId, Revision) exists.

Answer 2

Try this out, it returns the same results that you gave. The WITH statement sets up a CTE to query from. The ROW_NUMBER() function is partitioning function that does what you want:
;WITH BoxSets AS (
SELECT
ID
,BoxId
,Revision
,UnitValue
,UnitTypeId
,CASE WHEN UnitTypeId IN (1,2) THEN 1 ELSE 0 END ValidUnit
,ROW_NUMBER() OVER (PARTITION BY BoxID,UnitTypeID ORDER BY BoxID,UnitTypeID,UnitValue ) SetNumber
FROM Tracking
)
SELECT
b.ID
,b.BoxId
,b.Revision
,b.UnitValue
,b.UnitTypeId
,CASE ISNULL(b1.ValidUnits,0) WHEN 0 THEN NULL ELSE CASE b.SetNumber WHEN 1 THEN b.SetNumber ELSE NULL END END
FROM BoxSets AS b
LEFT JOIN (SELECT
BoxID
,SUM(ValidUnit) AS ValidUnits
FROM BoxSets
GROUP BY BoxId
HAVING SUM(ValidUnit) > 1) AS b1 ON b.BoxId = b1.BoxId