How to use GROUP BY to concatenate strings in SQL Server? - sql

Question

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

Answer 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

Answer 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

Answer 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.

Answer 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.

Answer 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

Answer 6

Install the SQLCLR Aggregates from http://groupconcat.codeplex.com
Then you can write code like this to get the result you asked for:
CREATE TABLE foo
(
id INT,
name CHAR(1),
Value CHAR(1)
);
INSERT INTO dbo.foo
(id, name, Value)
VALUES (1, 'A', '4'),
(1, 'B', '8'),
(2, 'C', '9');
SELECT id,
dbo.GROUP_CONCAT(name + ':' + Value) AS [Column]
FROM dbo.foo
GROUP BY id;

Answer 7

Eight years later... Microsoft SQL Server vNext Database Engine has finally enhanced Transact-SQL to directly support grouped string concatenation. The Community Technical Preview version 1.0 added the STRING_AGG function and CTP 1.1 added the WITHIN GROUP clause for the STRING_AGG function.
Reference: https://msdn.microsoft.com/en-us/library/mt775028.aspx

Answer 8

SQL Server 2005 and later allow you to create your own custom aggregate functions, including for things like concatenation- see the sample at the bottom of the linked article.

Answer 9

This is just an addition to Kevin Fairchild's post (very clever by the way). I would have added it as a comment, but I don't have enough points yet :)
I was using this idea for a view I was working on, however the items I was concatinating contained spaces. So I modified the code slightly to not use spaces as delimiters.
Again thanks for the cool workaround Kevin!
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],
REPLACE(REPLACE(REPLACE(
(SELECT [Name] + ':' + CAST([Value] AS VARCHAR(MAX)) as A
FROM #YourTable
WHERE ( ID = Results.ID )
FOR XML PATH (''))
, '</A><A>', ', ')
,'<A>','')
,'</A>','') AS NameValues
FROM #YourTable Results
GROUP BY ID
DROP TABLE #YourTable

Answer 10

An example would be
In Oracle you can use LISTAGG aggregate function.
Original records
name type
------------
name1 type1
name2 type2
name2 type3
Sql
SELECT name, LISTAGG(type, '; ') WITHIN GROUP(ORDER BY name)
FROM table
GROUP BY name
Result in
name type
------------
name1 type1
name2 type2; type3

Answer 11

This kind of question is asked here very often, and the solution is going to depend a lot on the underlying requirements:
https://stackoverflow.com/search?q=sql+pivot
and
https://stackoverflow.com/search?q=sql+concatenate
Typically, there is no SQL-only way to do this without either dynamic sql, a user-defined function, or a cursor.

Answer 12

Just to add to what Cade said, this is usually a front-end display thing and should therefore be handled there. I know that sometimes it's easier to write something 100% in SQL for things like file export or other "SQL only" solutions, but most of the times this concatenation should be handled in your display layer.

Answer 13

Don't need a cursor... a while loop is sufficient.
------------------------------
-- Setup
------------------------------
DECLARE #Source TABLE
(
id int,
Name varchar(30),
Value int
)
DECLARE #Target TABLE
(
id int,
Result varchar(max)
)
INSERT INTO #Source(id, Name, Value) SELECT 1, 'A', 4
INSERT INTO #Source(id, Name, Value) SELECT 1, 'B', 8
INSERT INTO #Source(id, Name, Value) SELECT 2, 'C', 9
------------------------------
-- Technique
------------------------------
INSERT INTO #Target (id)
SELECT id
FROM #Source
GROUP BY id
DECLARE #id int, #Result varchar(max)
SET #id = (SELECT MIN(id) FROM #Target)
WHILE #id is not null
BEGIN
SET #Result = null
SELECT #Result =
CASE
WHEN #Result is null
THEN ''
ELSE #Result + ', '
END + s.Name + ':' + convert(varchar(30),s.Value)
FROM #Source s
WHERE id = #id
UPDATE #Target
SET Result = #Result
WHERE id = #id
SET #id = (SELECT MIN(id) FROM #Target WHERE #id < id)
END
SELECT *
FROM #Target

Answer 14

Let's get very simple:
SELECT stuff(
(
select ', ' + x from (SELECT 'xxx' x union select 'yyyy') tb
FOR XML PATH('')
)
, 1, 2, '')
Replace this line:
select ', ' + x from (SELECT 'xxx' x union select 'yyyy') tb
With your query.

Answer 15

You can improve performance significant the following way if group by contains mostly one item:
SELECT
[ID],
CASE WHEN MAX( [Name]) = MIN( [Name]) THEN
MAX( [Name]) NameValues
ELSE
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
END
FROM #YourTable Results
GROUP BY ID

Answer 16

didn't see any cross apply answers, also no need for xml extraction. Here is a slightly different version of what Kevin Fairchild wrote. It's faster and easier to use in more complex queries:
select T.ID
,MAX(X.cl) NameValues
from #YourTable T
CROSS APPLY
(select STUFF((
SELECT ', ' + [Name] + ':' + CAST([Value] AS VARCHAR(MAX))
FROM #YourTable
WHERE (ID = T.ID)
FOR XML PATH(''))
,1,2,'') [cl]) X
GROUP BY T.ID

Answer 17

Using the Stuff and for xml path operator to concatenate rows to string :Group By two columns -->
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 (1,'B',5)
INSERT INTO #YourTable ([ID],[Name],[Value]) VALUES (2,'C',9)
-- retrieve each unique id and name columns and concatonate the values into one column
SELECT
[ID],
STUFF((
SELECT ', ' + [Name] + ':' + CAST([Value] AS VARCHAR(MAX)) -- CONCATONATES EACH APPLICATION : VALUE SET
FROM #YourTable
WHERE (ID = Results.ID and Name = results.[name] )
FOR XML PATH(''),TYPE).value('(./text())[1]','VARCHAR(MAX)')
,1,2,'') AS NameValues
FROM #YourTable Results
GROUP BY ID
SELECT
[ID],[Name] , --these are acting as the group by clause
STUFF((
SELECT ', '+ CAST([Value] AS VARCHAR(MAX)) -- CONCATONATES THE VALUES FOR EACH ID NAME COMBINATION
FROM #YourTable
WHERE (ID = Results.ID and Name = results.[name] )
FOR XML PATH(''),TYPE).value('(./text())[1]','VARCHAR(MAX)')
,1,2,'') AS NameValues
FROM #YourTable Results
GROUP BY ID, name
DROP TABLE #YourTable

Answer 18

Using Replace Function and FOR JSON PATH
SELECT T3.DEPT, REPLACE(REPLACE(T3.ENAME,'{"ENAME":"',''),'"}','') AS ENAME_LIST
FROM (
SELECT DEPT, (SELECT ENAME AS [ENAME]
FROM EMPLOYEE T2
WHERE T2.DEPT=T1.DEPT
FOR JSON PATH,WITHOUT_ARRAY_WRAPPER) ENAME
FROM EMPLOYEE T1
GROUP BY DEPT) T3
For sample data and more ways click here

Answer 19

If you have clr enabled you could use the Group_Concat library from GitHub

Answer 20

Another example without the garbage: ",TYPE).value('(./text())[1]','VARCHAR(MAX)')"
WITH t AS (
SELECT 1 n, 1 g, 1 v
UNION ALL
SELECT 2 n, 1 g, 2 v
UNION ALL
SELECT 3 n, 2 g, 3 v
)
SELECT g
, STUFF (
(
SELECT ', ' + CAST(v AS VARCHAR(MAX))
FROM t sub_t
WHERE sub_t.g = main_t.g
FOR XML PATH('')
)
, 1, 2, ''
) cg
FROM t main_t
GROUP BY g
Input-output is
************************* -> *********************
* n * g * v * * g * cg *
* - * - * - * * - * - *
* 1 * 1 * 1 * * 1 * 1, 2 *
* 2 * 1 * 2 * * 2 * 3 *
* 3 * 2 * 3 * *********************
*************************

Answer 21

I used this approach which may be easier to grasp. Get a root element, then concat to choices any item with the same ID but not the 'official' name
Declare #IdxList as Table(id int, choices varchar(max),AisName varchar(255))
Insert into #IdxLIst(id,choices,AisName)
Select IdxId,''''+Max(Title)+'''',Max(Title) From [dbo].[dta_Alias]
where IdxId is not null group by IdxId
Update #IdxLIst
set choices=choices +','''+Title+''''
From #IdxLIst JOIN [dta_Alias] ON id=IdxId And Title <> AisName
where IdxId is not null
Select * from #IdxList where choices like '%,%'

Answer 22

For all my healthcare folks out there:
SELECT
s.NOTE_ID
,STUFF ((
SELECT
[note_text] + ' '
FROM
HNO_NOTE_TEXT s1
WHERE
(s1.NOTE_ID = s.NOTE_ID)
ORDER BY [line] ASC
FOR XML PATH(''),TYPE).value('(./text())[1]','VARCHAR(MAX)')
,
1,
2,
'') AS NOTE_TEXT_CONCATINATED
FROM
HNO_NOTE_TEXT s
GROUP BY NOTE_ID