Easy To Understand | MySQL Solution |
```\nSELECT event_day AS day,  emp_id,  \nSUM(out_time - in_time) AS total_time\nFROM Employees GROUP BY 1, 2;
```\nSELECT event_day AS day,  emp_id,  \nSUM(out_time - in_time) AS total_time\nFROM Employees GROUP BY 1, 2;
['MySQL']