Any body know the query about this senario

Question

Name | Gender -------------- 
A | F 
B | M 
C | F 
D | F 
E | M

From the above data, gender was wrongly entered, which means in place of F it should be M and in place of M it should F. How to update whole table with a single line sql query (don't use pl/sql block). Since, if I will update gender column one by one, then possible error would be all rows values of gender column becomes either F or M.
Final output should be

Name | Gender -------------- 
A | M 
B | F 
C | M 
D | M
 E | F 

Answer 1

declare @Table TABLE ( Id int, Value char(1) )
insert into @Table
select 1, 'F'
union select 2, 'F'
union select 3, 'F'
union select 4, 'M'
union select 5, 'M'
union select 6, 'M'
select * from @Table
update @Table set Value = case when Value = 'F' then 'M' when Value = 'M' then 'F' else Value End
select * from @Table​