Sorting varchar field with mixed alphanumeric data - sql-server

Question

I searched and read a lot of answers on here, but can't find one that will answer my problem, (or help me to find the answer on my own).
We have a table which contains a varchar display field, who's data is entered by the customer.
When we display the results, our customer wants the results to be ordered "correctly".
A sample of what the data could like is as follows:
"AAA 2 1 AAA"
"AAA 10 1 AAA"
"AAA 10 2 BAA"
"AAA 101 1 AAA"
"BAA 101 2 BBB"
"BAA 101 10 BBB"
"BAA 2 2 AAA"
Sorting by this column ASC returns:
1: "AAA 10 1 AAA"
2: "AAA 10 2 BAA"
3: "AAA 101 1 AAA"
4: "AAA 2 1 AAA"
5: "BAA 101 10 BBB"
6: "BAA 101 2 BBB"
7: "BAA 2 2 AAA"
The customer would like row 4 to actually be the first row (as 2 comes before 10), and similarly row 7 to be between rows 4 and 5, as shown below:
1: "AAA 2 1 AAA"
2: "AAA 10 1 AAA"
3: "AAA 10 2 BAA"
4: "AAA 101 1 AAA"
5: "BAA 2 2 AAA"
6: "BAA 101 10 BBB"
7: "BAA 101 2 BBB"
Now, the real TRICKY bit is, there is no hard and fast rule to what the data will look like in this column; it is entirely down to the customer as to what they put in here (the data shown above is just arbitrary to demonstrate the problem).
Any Help?
EDIT:
learning that this is referred to as "natural sorting" has improved my search results massively
I'm going to give the accepted answer to this question a bash and will update accordingly:
Natural (human alpha-numeric) sort in Microsoft SQL 2005

Answer 1

First create this function
Create FUNCTION dbo.SplitAndJoin
(
#delimited nvarchar(max),
#delimiter nvarchar(100)
) RETURNS Nvarchar(Max)
AS
BEGIN
declare #res nvarchar(max)
declare #t TABLE
(
-- Id column can be commented out, not required for sql splitting string
id int identity(1,1), -- I use this column for numbering splitted parts
val nvarchar(max)
)
declare #xml xml
set #xml = N'<root><r>' + replace(#delimited,#delimiter,'</r><r>') + '</r></root>'
insert into #t(val)
select
r.value('.','varchar(max)') as item
from #xml.nodes('//root/r') as records(r)
SELECT #res = STUFF((SELECT ' ' + case when isnumeric(val) = 1 then RIGHT('00000000'+CAST(val AS VARCHAR(8)),8) else val end
FROM #t
FOR XML PATH('')), 1, 1, '')
RETURN #Res
END
GO
This function gets an space delimited string and split it to words then join them together again by space but if the word is number it adds 8 leading zeros
then you use this query
Select * from Test
order by dbo.SplitAndJoin(col1,' ')
Live result on SQL Fiddle

Answer 2

Without consistency, you only have brute force
Without rules, your brute force is limited
I've made some assumptions with this code: if it starts with 3 alpha characters, then a space, then a number (up to 3 digits), let's treat it differently.
There's nothing special about this - it is just string manipulation being brute forced in to giving you "something". Hopefully it illustrates how painful this is without having consistency and rules!
DECLARE #t table (
a varchar(50)
);
INSERT INTO #t (a)
VALUES ('AAA 2 1 AAA')
, ('AAA 10 1 AAA')
, ('AAA 10 2 BAA')
, ('AAA 101 1 AAA')
, ('BAA 101 2 BBB')
, ('BAA 101 10 BBB')
, ('BAA 2 2 AAA')
, ('Completely different')
;
; WITH step1 AS (
SELECT a
, CASE WHEN a LIKE '[A-Z][A-Z][A-Z] [0-9]%' THEN 1 ELSE 0 END As fits_pattern
, CharIndex(' ', a) As first_space
FROM #t
)
, step2 AS (
SELECT *
, CharIndex(' ', a, first_space + 1) As second_space
, CASE WHEN fits_pattern = 1 THEN Left(a, 3) ELSE 'ZZZ' END As first_part
, CASE WHEN fits_pattern = 1 THEN SubString(a, first_space + 1, 1000) ELSE 'ZZZ' END As rest_of_it
FROM step1
)
, step3 AS (
SELECT *
, CASE WHEN fits_pattern = 1 THEN SubString(rest_of_it, 1, second_space - first_space - 1) ELSE 'ZZZ' END As second_part
FROM step2
)
SELECT *
, Right('000' + second_part, 3) As second_part_formatted
FROM step3
ORDER
BY first_part
, second_part_formatted
, a
;
Relevant, sorted results:
a
---------------------
AAA 2 1 AAA
AAA 10 1 AAA
AAA 10 2 BAA
AAA 101 1 AAA
BAA 2 2 AAA
BAA 101 10 BBB
BAA 101 2 BBB
Completely different
This code can be vastly improved/shortened. I've just left it verbose in order to give you some clarity over the steps taken.