SQL PIVOT on a variable amount of rows - sql-server

Question

I have the following data on a MSSQL Server:
Item No_ Unit Of Measure Qty Per Base UoM Rounding Precision
000001 PIECE 1 1.0
000001 PALLET 100 1.0
000001 BOX 12 1.0
000002 KG 1 1.0
000002 TON 1000 0.001
I am trying to get the following output:
Item No_ UoM1 Qty pb UoM1 RP1 UoM2 Qty pb UoM2 RP2 UoM3 Qty pb UoM3 RP3
000001 PIECE 1 1.0 PALLET 100 1.0 BOX 12 1.0
000002 KG 1 1.0 TON 1000 0.0001 NULL NULL NULL
I tried achieving this using the PIVOT operator but it does not seem te be correct.
What is the correct way to achieve my desired output?

Answer 1

For trully generic solution you need to use Dynamic-SQL.
But you say you want starting point, so I give you one. You can use:
LiveDemo
WITH cte AS
(
SELECT *, ROW_NUMBER() OVER(PARTITION BY Item_No_ ORDER BY (SELECT 1)) AS rn
FROM #mytable
)
select Item_No_,
max(case when rn = 1 then Unit_Of_Measure end) UoM1,
max(case when rn = 1 then Qty_Per_Base_UoM end) [Qty pb UoM1],
max(case when rn = 1 then Rounding_Precision end) RP1,
max(case when rn = 2 then Unit_Of_Measure end) UoM2,
max(case when rn = 2 then Qty_Per_Base_UoM end) [Qty pb UoM2],
max(case when rn = 2 then Rounding_Precision end) RP2,
max(case when rn = 3 then Unit_Of_Measure end) UoM3,
max(case when rn = 3 then Qty_Per_Base_UoM end) [Qty pb UoM3],
max(case when rn = 3 then Rounding_Precision end) RP3,
max(case when rn = 4 then Unit_Of_Measure end) UoM4,
max(case when rn = 4 then Qty_Per_Base_UoM end) [Qty pb UoM4],
max(case when rn = 4 then Rounding_Precision end) RP4
from cte
group by Item_No_;
The point is that if your number of units is known in advance you can create hardcoded columns from 1 .. n.
For more info search Dynamic Pivot multiple columns. It is achievable, but first try to crack this solution.