yes, you can just include the column you would like to order..
DECLARE @Table table( sno int, sname varchar(200))
INSERT INTO @Table(sno,sname)
VALUES (1,'1Test'),(2,'2Test'),(3,'3Test')
SELECT * FROM @table WHERE sno = 2
UNION
SELECT * FROM @table WHERE sno = 1
UNION
SELECT * FROM @table WHERE sno = 3
ORDER BY sno desc
Hope it Helps!!