SQL Server solution
\nUpdate salary\nSET sex = CASE\nWHEN sex = \'m\' then \'f\'\nwhen sex = \'f\' then \'m\'\nELSE sex end\n
```\nUpdate salary\nSET sex = CASE\nWHEN sex = \'m\' then \'f\'\nwhen sex = \'f\' then \'m\'\nELSE sex end\n```
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