SQL to create single record from Multiple rows

SQL_Single _from_multiple_row

Scenario :
SubjectID       StudentName
----------      -------------
1               Mary
1               John
1               Sam
2               Alaina
2               Edward

To

SubjectID       StudentName
----------      -------------
1               Mary, John, Sam
2               Alaina, Edward

Select distinct ST2.SubjectID, 
               substring((Select ','+ST1.StudentName  AS [text()]
                From dbo.Students ST1
                Where ST1.SubjectID = ST2.SubjectID
                ORDER BY ST1.SubjectID
                For XML PATH ('')),2, 1000) [Students]
         From dbo.Students ST2