questing regarding the row value interchange

-- Create sample table.

create table Interchanges
(rowNum  int,
 rowvalue  varchar(40))

-- insert sample data
 insert into Interchanges(rownum,rowvalue) values (1,'row1')
 insert into Interchanges(rownum,rowvalue) values (2,'row2')
 insert into Interchanges(rownum,rowvalue) values (3,'row3')
 insert into Interchanges(rownum,rowvalue) values (4,'row4')
 insert into Interchanges(rownum,rowvalue) values (5,'row5')
 insert into Interchanges(rownum,rowvalue) values (6,'row6')

-- Select query 
SELECT  * FROM Interchanges 

-- The out but will be like this : 
--rowNum         rowvalue
--1		row2
--2		row1
--3		row4
--4		row3
--5		row6
--6		row5

-- Used CTE to update swap row data
-- run both cte and update query at same time

;with cte as
   (
     SELECT distinct rownum ,case when rownum+1=2 then 2 else rownum+1 end as rownewval, rowvalue FROM Interchanges  WHERE rownum % 2 = 1  
   UNION  ALL
   SELECT distinct rownum ,case when rownum-1=0 then 1 else rownum-1 end as rownewval, rowvalue FROM Interchanges  WHERE rownum % 2 = 0 
    )
update Interchanges set
Interchanges.rowvalue= upval.rowvalue
from Interchanges  ,cte upval
where Interchanges.rownum=upval.rownewval

-- Select query 
SELECT  * FROM Interchanges 

-- The Final result as you expected

----rowNum             rowvalue
--1			row2
--2			row1
--3			row4
--4			row3
--5			row6
--6			row5