Get every combination of sort order and value of a csv - sql

Question

If I have a string with numbers separated by commas, like this:
Declare #string varchar(20) = '123,456,789'
And would like to return every possible combination + sort order of the values by doing this:
Select Combination FROM dbo.GetAllCombinations(#string)
Which would in result return this:
123
456
789
123,456
456,123
123,789
789,123
456,789
789,456
123,456,789
123,789,456
456,789,123
456,123,789
789,456,123
789,123,456
As you can see not only is every combination returned, but also each combination+sort order as well. The example shows only 3 values separated by commas, but should parse any amount--Recursive.
The logic needed would be somewhere in the realm of using a WITH CUBE statement, but the problem with using WITH CUBE (in a table structure instead of CSV of course), is that it won't shuffle the order of the values 123,456 456,123 etc., and will only provide each combination, which is only half of the battle.
Currently I have no idea what to try. If someone can provide some assistance it would be appreciated.

Answer 1

I use a User Defined Table-valued Function called split_delimiter that takes 2 values: the #delimited_string and the #delimiter_type.
CREATE FUNCTION [dbo].[split_delimiter](#delimited_string VARCHAR(8000), #delimiter_type CHAR(1))
RETURNS TABLE AS
RETURN
WITH cte10(num) AS
(
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1
)
,cte100(num) AS
(
SELECT 1
FROM cte10 t1, cte10 t2
)
,cte10000(num) AS
(
SELECT 1
FROM cte100 t1, cte100 t2
)
,cte1(num) AS
(
SELECT TOP (ISNULL(DATALENGTH(#delimited_string),0)) ROW_NUMBER() OVER (ORDER BY (SELECT NULL))
FROM cte10000
)
,cte2(num) AS
(
SELECT 1
UNION ALL
SELECT t.num+1
FROM cte1 t
WHERE SUBSTRING(#delimited_string,t.num,1) = #delimiter_type
)
,cte3(num,[len]) AS
(
SELECT t.num
,ISNULL(NULLIF(CHARINDEX(#delimiter_type,#delimited_string,t.num),0)-t.num,8000)
FROM cte2 t
)
SELECT delimited_item_num = ROW_NUMBER() OVER(ORDER BY t.num)
,delimited_value = SUBSTRING(#delimited_string, t.num, t.[len])
FROM cte3 t;
Using that I was able to parse the CSV to a table and join it back to itself multiple times and use WITH ROLLUP to get the permutations you are looking for.
WITH Numbers as
(
SELECT delimited_value
FROM dbo.split_delimiter('123,456,789',',')
)
SELECT CAST(Nums1.delimited_value AS VARCHAR)
,ISNULL(CAST(Nums2.delimited_value AS VARCHAR),'')
,ISNULL(CAST(Nums3.delimited_value AS VARCHAR),'')
,CAST(Nums4.delimited_value AS VARCHAR)
FROM Numbers as Nums1
LEFT JOIN Numbers as Nums2
ON Nums2.delimited_value not in (Nums1.delimited_value)
LEFT JOIN Numbers as Nums3
ON Nums3.delimited_value not in (Nums1.delimited_value, Nums2.delimited_value)
LEFT JOIN Numbers as Nums4
ON Nums4.delimited_value not in (Nums1.delimited_value, Nums2.delimited_value, Nums3.delimited_value)
GROUP BY CAST(Nums1.delimited_value AS VARCHAR)
,ISNULL(CAST(Nums2.delimited_value AS VARCHAR),'')
,ISNULL(CAST(Nums3.delimited_value AS VARCHAR),'')
,CAST(Nums4.delimited_value AS VARCHAR) WITH ROLLUP
If you will potentially have more than 3 or 4, you'll want to expand your code accordingly.