String split on multiple fields to one result - sql

Question

I have a table that looks like the below set as a field for one value:
|---------------------|------------------|------------------|
| Colour | Amount | Size |
|---------------------|------------------|------------------|
| Black,Blue,Green | 1,2,2 | 100,100,100 |
|---------------------|------------------|------------------|
I need to do a string split on each of them and return it in one go.
I've currently got this and works for colour:
SELECT value as colour
FROM [table_name]
CROSS APPLY STRING_SPLIT(colour, ',')
I can't figure out how to do multiple string splits in one go. It should return it as this then:
|---------------------|------------------|------------------|
| Colour | Amount | Size |
|---------------------|------------------|------------------|
| Black | 1 | 100 |
|---------------------|------------------|------------------|
| Blue | 2 | 100 |
|---------------------|------------------|------------------|
| Green | 2 | 100 |
|---------------------|------------------|------------------|
Any help would be great!

Answer 1

Unfortunately, string_split() doesn't provide the option to preserve the order of the substrings it produces. Hence, that is very, very tricky to use in this case.
I prefer a recursive CTE (until the function gets fixed):
with cte as (
select convert(varchar(max), null) as color,
convert(varchar(max), null) as amount,
convert(varchar(max), null) as size,
convert(varchar(max), colors + ',') as rest_colors,
convert(varchar(max), amounts + ',') as rest_amounts ,
convert(varchar(max), sizes + ',') as rest_sizes,
0 as lev
from t
union all
select left(rest_colors, charindex(',', rest_colors) - 1),
left(rest_amounts, charindex(',', rest_amounts) - 1),
left(rest_sizes, charindex(',', rest_sizes) - 1),
stuff(rest_colors, 1, charindex(',', rest_colors), ''),
stuff(rest_amounts, 1, charindex(',', rest_amounts), ''),
stuff(rest_sizes, 1, charindex(',', rest_sizes), ''),
lev + 1
from cte
where rest_colors <> ''
)
select color, amount, size
from cte
where lev > 0;
Here is a db<>fiddle.

Answer 2

As Gordon mentioned, string_split() does not GTD sequence. That said, and if you are open to a Table-Value Function, consider the following where we UNPIVOT your data and then apply a final PIVOT. Note: The RN = ... could be replaced with your own ID (if you have one)
I adjusted the values to illustrate there is a proper sequencing.
Example
;with cte as (
Select RN = row_number() over (order by (select null))
,[Colour]
,[Amount]
,[Size]
From YourTable
)
Select *
From (
Select RN,Item='Colour',B.* From cte Cross Apply [dbo].[tvf-Str-Parse](Colour,',') B
Union All
Select RN,Item='Amount',B.* From cte Cross Apply [dbo].[tvf-Str-Parse](Amount,',') B
Union All
Select RN,Item='Size' ,B.* From cte Cross Apply [dbo].[tvf-Str-Parse](Size ,',') B
) src
Pivot ( max(RetVal) for Item in ([Colour],[Amount],[Size] ) ) pvt
Returns
RN RetSeq Colour Amount Size
1 1 Black 1 100
1 2 Blue 2 200
1 3 Green 3 300
The Function if Interested
CREATE FUNCTION [dbo].[tvf-Str-Parse] (#String varchar(max),#Delimiter varchar(10))
Returns Table
As
Return (
Select RetSeq = row_number() over (order by 1/0)
,RetVal = ltrim(rtrim(B.i.value('(./text())[1]', 'varchar(max)')))
From (Select x = Cast('<x>' + replace((Select replace(#String,#Delimiter,'§§Split§§') as [*] For XML Path('')),'§§Split§§','</x><x>')+'</x>' as xml).query('.')) as A
Cross Apply x.nodes('x') AS B(i)
);