Solution with Update & Case - Accepted
\nUPDATE salary SET sex = (CASE WHEN sex = \'m\' THEN \'f\'\n                              WHEN sex = \'f\' THEN \'m\'\n                              else sex\n
```\nUPDATE salary SET sex = (CASE WHEN sex = \'m\' THEN \'f\'\n                              WHEN sex = \'f\' THEN \'m\'\n                              else sex\n                        END);```\n\t\t\t\t\t\t\t\t\t\t
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