Single updation change gender type

Create table empGender(eid int,ename varchar(20),eGender varchar(1))

insert into empGender values(1,'Raju','M')

insert into empGender values(2,'mura','M')

insert into empGender values(3,'kiran','M')

insert into empGender values(4,'rani','M')

insert into empGender values(5,'vani','F')

insert into empGender values(6,'ramya','F')

select * from empgender

update empgender set eGender=case eGender when 'M' Then 'F'   ELSE 'M' END            

select * from empgender