oracle
\nselect \n     to_char(event_day,\'YYYY-MM-DD\') as day\n    ,emp_id\n    ,sum(out_time - in_time) as total_time\nfrom employees\ngroup by to_char(event_day,\'
```\nselect \n     to_char(event_day,\'YYYY-MM-DD\') as day\n    ,emp_id\n    ,sum(out_time - in_time) as total_time\nfrom employees\ngroup by to_char(event_day,\'YYYY-MM-DD\'), emp_id;\n```
['Oracle']