How to get distinct values in 2 columns in SQL server table

1 Way:  


Select CERTID ,APPID
   FROM
   (
     Select CERTID, APPID,
ROW_NUMBER() OVER(PARTITION BY APPID ORDER BY CERTID Asc) rn
From  Table1)s
Where rn =1
ORDER BY CERTID 


2nd way:




Select MIN(CERTID ) CERTID , APPID 
from Table1
Group BY APPID