How to use GROUP BY to concatenate strings in SQL Server?
Solution 1
No CURSOR, WHILE loop, or User-Defined Function needed.
Just need to be creative with FOR XML and PATH.
[Note: This solution only works on SQL 2005 and later. Original question didn't specify the version in use.]
CREATE TABLE #YourTable ([ID] INT, [Name] CHAR(1), [Value] INT)
INSERT INTO #YourTable ([ID],[Name],[Value]) VALUES (1,'A',4)
INSERT INTO #YourTable ([ID],[Name],[Value]) VALUES (1,'B',8)
INSERT INTO #YourTable ([ID],[Name],[Value]) VALUES (2,'C',9)
SELECT
[ID],
STUFF((
SELECT ', ' + [Name] + ':' + CAST([Value] AS VARCHAR(MAX))
FROM #YourTable
WHERE (ID = Results.ID)
FOR XML PATH(''),TYPE).value('(./text())[1]','VARCHAR(MAX)')
,1,2,'') AS NameValues
FROM #YourTable Results
GROUP BY ID
DROP TABLE #YourTable
Solution 2
If it is SQL Server 2017 or SQL Server Vnext, SQL Azure you can use string_agg
as below:
select id, string_agg(concat(name, ':', [value]), ', ')
from #YourTable
group by id
Solution 3
using XML path will not perfectly concatenate as you might expect... it will replace "&" with "&" and will also mess with <" and ">
...maybe a few other things, not sure...but you can try this
I came across a workaround for this... you need to replace:
FOR XML PATH('')
)
with:
FOR XML PATH(''),TYPE
).value('(./text())[1]','VARCHAR(MAX)')
...or NVARCHAR(MAX)
if thats what youre using.
why the hell doesn't SQL
have a concatenate aggregate function? this is a PITA.
Solution 4
I ran into a couple of problems when I tried converting Kevin Fairchild's suggestion to work with strings containing spaces and special XML characters (&
, <
, >
) which were encoded.
The final version of my code (which doesn't answer the original question but may be useful to someone) looks like this:
CREATE TABLE #YourTable ([ID] INT, [Name] VARCHAR(MAX), [Value] INT)
INSERT INTO #YourTable ([ID],[Name],[Value]) VALUES (1,'Oranges & Lemons',4)
INSERT INTO #YourTable ([ID],[Name],[Value]) VALUES (1,'1 < 2',8)
INSERT INTO #YourTable ([ID],[Name],[Value]) VALUES (2,'C',9)
SELECT [ID],
STUFF((
SELECT ', ' + CAST([Name] AS VARCHAR(MAX))
FROM #YourTable WHERE (ID = Results.ID)
FOR XML PATH(''),TYPE
/* Use .value to uncomment XML entities e.g. > < etc*/
).value('.','VARCHAR(MAX)')
,1,2,'') as NameValues
FROM #YourTable Results
GROUP BY ID
DROP TABLE #YourTable
Rather than using a space as a delimiter and replacing all the spaces with commas, it just pre-pends a comma and space to each value then uses STUFF
to remove the first two characters.
The XML encoding is taken care of automatically by using the TYPE directive.
Solution 5
Another option using Sql Server 2005 and above
---- test data
declare @t table (OUTPUTID int, SCHME varchar(10), DESCR varchar(10))
insert @t select 1125439 ,'CKT','Approved'
insert @t select 1125439 ,'RENO','Approved'
insert @t select 1134691 ,'CKT','Approved'
insert @t select 1134691 ,'RENO','Approved'
insert @t select 1134691 ,'pn','Approved'
---- actual query
;with cte(outputid,combined,rn)
as
(
select outputid, SCHME + ' ('+DESCR+')', rn=ROW_NUMBER() over (PARTITION by outputid order by schme, descr)
from @t
)
,cte2(outputid,finalstatus,rn)
as
(
select OUTPUTID, convert(varchar(max),combined), 1 from cte where rn=1
union all
select cte2.outputid, convert(varchar(max),cte2.finalstatus+', '+cte.combined), cte2.rn+1
from cte2
inner join cte on cte.OUTPUTID = cte2.outputid and cte.rn=cte2.rn+1
)
select outputid, MAX(finalstatus) from cte2 group by outputid
Comments
-
Eldila about 3 years
How do I get:
id Name Value 1 A 4 1 B 8 2 C 9
to
id Column 1 A:4, B:8 2 C:9