Microsoft SQL Server String Aggregate functions in SQL Server Using STUFF for string aggregation
Example
We have a Student table with SubjectId. Here the requirement is to concatenate based on subjectId.
All SQL Server versions
create table #yourstudent (subjectid int, studentname varchar(10))
insert into #yourstudent (subjectid, studentname) values
( 1 ,'Mary' )
,( 1 ,'John' )
,( 1 ,'Sam' )
,( 2 ,'Alaina')
,( 2 ,'Edward')
select subjectid, stuff(( select concat( ',', studentname) from #yourstudent y where y.subjectid = u.subjectid for xml path('')),1,1, '')
from #yourstudent u
group by subjectid
