Constructing row values into comma-separate string

 ---Create Table

CREATE TABLE #USER (USERNAME VARCHAR(25))

---Inserting Values

INSERT INTO #USER (USERNAME) VALUES ('Loki')

INSERT INTO #USER (USERNAME) VALUES ('Chinnu')

INSERT INTO #USER (USERNAME) VALUES ('Chinni')

INSERT INTO #USER (USERNAME) VALUES ('Laddu')

---Constricting comma-separate string

SELECT DISTINCT STUFF((SELECT ',' +USERNAME  FROM #user  FOR XML PATH ('')),1,1,'')AS LIST FROM #user

--- Drop table

DROP TABLE #USER