I have a field in my database that contains strings, separated by comma:
select [MyField] from dbo.[MyDatabase];
MyField
-------
A, B, C
C, B, D, A
A, C, H, Z, J
K, A
What I need is to return these strings, but ordered alphabetically:
MyField
-------
A, B, C
A, B, C, D
A, C, H, J, Z
A, K
How can I achieve this in the same select query?
As pointed out by Larnu in the comments, you really should fix your broken data model, and change that column into a table, with a one-to-many relationship to the original table.
Having said that, I realize that sometimes this simply can't be done, for a variety of reasons - and because of that, I can suggest a workaround in case you can't fix the database structure.
That workaround includes breaking that string of comma-delimited values to a table, and select from that table in an alphabetical order, concatenating the values from the different rows as you go.
Note: This will probably have poor performance, but it is a direct result of the broken data model.
First, create and populate sample table(Please save us this step in your future questions):
DECLARE @T AS TABLE (
Col1 varchar(13)
);
INSERT INTO @T (Col1) VALUES
('A, B, C'),
('C, B, D, A'),
('A, C, H, Z, J'),
('K, A');
Then, use a UDF to break the comma delimited string into a table. I'm using Jeff Moden's splitter, but you can choose your own.
CREATE FUNCTION [dbo].[DelimitedSplit8K]
--===== Define I/O parameters
(@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
;
Once you have a string splitter, use the stuff + for xml path technique to reconstruct the final string from the rows returned by the string splitter:
SELECT Col1, STUFF((
SELECT ', '+ RTRIM(LTRIM(Item))
FROM [dbo].[DelimitedSplit8K](Col1, ', ')
ORDER BY RTRIM(LTRIM(Item))
FOR XML PATH('')
), 1, 2, '') As Ordered
FROM @T
Results:
Col1 Ordered
A, B, C A, B, C
C, B, D, A A, B, C, D
A, C, H, Z, J A, C, H, J, Z
K, A A, K
