SQL Solution, easy One-liner, Memory usage less than 100%
\nUpdate Salary SET sex= CASE when sex=\'m\' then \'f\' when sex=\'f\' then \'m\' END;\n
```\nUpdate Salary SET sex= CASE when sex=\'m\' then \'f\' when sex=\'f\' then \'m\' END;\n```
['MySQL']