Use of If Condition in Select Query

Use like this:

SELECT Name_Of_Head,Name_Of_Father, iif(tot_score>13,'APL','BPL') as Class
FROM FAMILY;


SELECT Name_Of_Head,Name_Of_Father,iif(Social_Group=1,'A',iif(Social_Group=2,'B',iif(Social_Group=3,'C',iif(Social_Group=4,'D','')))) as Caste
FROM FAMILY;