Short and Simple
\nUPDATE salary\n    SET sex  = (CASE WHEN sex = 'm' \n        THEN  'f' \n        ELSE 'm' \n        END)\n
```\nUPDATE salary\n    SET sex  = (CASE WHEN sex = 'm' \n        THEN  'f' \n        ELSE 'm' \n        END)\n```
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