Ordering a Delimited Column by Section - sql

Question

I need to order a column sequentially by each delimited section. For example, given the sample data:
a
----------
120.1
120.2
120.12
120
130
120.2.22
120.2.41
120.3
I need to obtain the following output:
120
120.1
120.2
120.2.22
120.2.41
120.3
120.12
130
I use this query but its doesn't work
Query ;
Select a from b rpad(REPLACE(a, '.', ''),15,0),REPLACE(a, '.', '') ASC

Answer 1

I agree with all the comments from Sean Lange et al. Since you can have unlimited number of decimals, you need a splitter. Once the values are split, then you could apply the same ORDER BY logic I have shown. I think the ORDER BY really explains the algorithm you were looking for.
Here is a way with a splitter:
declare #table table (col varchar(64))
insert into #table
values
('120.1'),
('120.2'),
('120.12'),
('120'),
('130'),
('120.2.22'),
('120.2.41.55.64.12'),
('120.3')
;with cte as(
select
*
from #table t
cross apply dbo.DelimitedSplit8K(t.col,'.')
pivot(
max(Item) for ItemNumber in ([1],[2],[3],[4],[5],[6],[7],[8]) --enter the number of possibilities
) p)
select
cte.*
from cte
order by
cast(isnull(cte.[1],0) as int)
,cast(isnull(cte.[2],0) as int)
,cast(isnull(cte.[3],0) as int)
,cast(isnull(cte.[4],0) as int)
,cast(isnull(cte.[5],0) as int)
,cast(isnull(cte.[6],0) as int)
,cast(isnull(cte.[7],0) as int)
,cast(isnull(cte.[8],0) as int)
The function, if needed:
CREATE FUNCTION [dbo].[DelimitedSplit8K] (#pString VARCHAR(8000), #pDelimiter CHAR(1))
--WARNING!!! DO NOT USE MAX DATA-TYPES HERE! IT WILL KILL PERFORMANCE!
RETURNS TABLE WITH SCHEMABINDING AS
RETURN
/* "Inline" CTE Driven "Tally Table" produces values from 1 up to 10,000... enough to cover VARCHAR(8000)*/
WITH E1(N) 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
), --10E+1 or 10 rows
E2(N) AS (SELECT 1 FROM E1 a, E1 b), --10E+2 or 100 rows
E4(N) AS (SELECT 1 FROM E2 a, E2 b), --10E+4 or 10,000 rows max
cteTally(N) AS (--==== This provides the "base" CTE and limits the number of rows right up front
-- for both a performance gain and prevention of accidental "overruns"
SELECT TOP (ISNULL(DATALENGTH(#pString),0)) ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) FROM E4
),
cteStart(N1) AS (--==== This returns N+1 (starting position of each "element" just once for each delimiter)
SELECT 1 UNION ALL
SELECT t.N+1 FROM cteTally t WHERE SUBSTRING(#pString,t.N,1) = #pDelimiter
),
cteLen(N1,L1) AS(--==== Return start and length (for use in substring)
SELECT s.N1,
ISNULL(NULLIF(CHARINDEX(#pDelimiter,#pString,s.N1),0)-s.N1,8000)
FROM cteStart s
)
--===== Do the actual split. The ISNULL/NULLIF combo handles the length for the final element when no delimiter is found.
SELECT ItemNumber = ROW_NUMBER() OVER(ORDER BY l.N1),
Item = SUBSTRING(#pString, l.N1, l.L1)
FROM cteLen l
GO

Answer 2

First create a function to split. I stole this one from https://sqlperformance.com/2012/07/t-sql-queries/split-strings
create FUNCTION dbo.SplitStrings_XML
(
#List NVARCHAR(MAX),
#Delimiter NVARCHAR(255)
)
RETURNS TABLE
WITH SCHEMABINDING
AS
RETURN
(
SELECT rn=row_number() over (order by i), Item = y.i.value('(./text())[1]', 'nvarchar(4000)')
FROM
(
SELECT x = CONVERT(XML, '<i>'
+ REPLACE(#List, #Delimiter, '</i><i>')
+ '</i>').query('.')
) AS a CROSS APPLY x.nodes('i') AS y(i)
);
GO
declare #t table (a varchar(64))
insert into #t
values
('120.1'),
('120.2'),
('120.12'),
('120'),
('130'),
('120.2.22'),
('120.2.41'),
('120.3')
select a
, a1 = max(cast(case when rn=1 then Item else null end as int))
, a2 = max(cast(case when rn=2 then Item else null end as int))
, a3 = max(cast(case when rn=3 then Item else null end as int))
, a4 = max(cast(case when rn=4 then Item else null end as int))
from #t t
cross apply dbo.SplitStrings_XML(t.a,'.') as a
group by t.a
order by 2,3,4,5