Hi iammann,
Refer the below sample query. You need to convert the fields like int to varchar to concadinate.
DECLARE @Test AS TABLE(ID INT,FIRSTNAME VARCHAR(50),LASTNAME VARCHAR(50),AGE INT)
INSERT INTO @Test VALUES(1,'Ram','Singh',25)
INSERT INTO @Test VALUES(2,'Rahim','Khan',38)
INSERT INTO @Test VALUES(3,'David','Morkel',52)
INSERT INTO @Test VALUES(NULL,NULL,NULL,NULL)
SELECT  ISNULL(CONVERT(VARCHAR(50),ID),'') + ',' +
        ISNULL(FIRSTNAME,'') + ',' +
        ISNULL(LASTNAME,'') + ',' +
        ISNULL(CONVERT(VARCHAR(50),AGE),'') AS BusiNessfocus 
FROM @Test
Output
| BusiNessfocus | 
| 1,Ram,Singh,25 | 
| 2,Rahim,Khan,38 | 
| 3,David,Morkel,52 | 
| ,,, |