[sql-server] Multiple rows to one comma-separated value in Sql Server

Test Data

DECLARE @Table1 TABLE(ID INT, Value INT)
INSERT INTO @Table1 VALUES (1,100),(1,200),(1,300),(1,400)

Query

SELECT  ID
       ,STUFF((SELECT ', ' + CAST(Value AS VARCHAR(10)) [text()]
         FROM @Table1 
         WHERE ID = t.ID
         FOR XML PATH(''), TYPE)
        .value('.','NVARCHAR(MAX)'),1,2,' ') List_Output
FROM @Table1 t
GROUP BY ID

Result Set

+--------------------------+
¦ ID ¦     List_Output     ¦
¦----+---------------------¦
¦  1 ¦  100, 200, 300, 400 ¦
+--------------------------+

SQL Server 2017 and Later Versions

If you are working on SQL Server 2017 or later versions, you can use built-in SQL Server Function STRING_AGG to create the comma delimited list:

DECLARE @Table1 TABLE(ID INT, Value INT);
INSERT INTO @Table1 VALUES (1,100),(1,200),(1,300),(1,400);


SELECT ID , STRING_AGG([Value], ', ') AS List_Output
FROM @Table1
GROUP BY ID;

Result Set

+--------------------------+
¦ ID ¦     List_Output     ¦
¦----+---------------------¦
¦  1 ¦  100, 200, 300, 400 ¦
+--------------------------+