mysql replace values in a table

update users set gender=case when gender='male' then 'female' else 'male' end where gender in ('male','female');

UPDATE users SET gender='tmp' WHERE gender='male';

UPDATE users SET gender='male' WHERE gender='female';

UPDATE users SET gender='female' WHERE gender='tmp';

Combine two queries into one :-

update users set gender = if (gender='female', 'male', 'female');