PostgreSQL|Beats 91%|Simple solution with GROUP BY
Intuition\n Describe your first thoughts on how to solve this problem. \n\n# Approach\n Describe your approach to solving the problem. \n\n# Complexity\n- Time 
# Intuition\n<!-- Describe your first thoughts on how to solve this problem. -->\n\n# Approach\n<!-- Describe your approach to solving the problem. -->\n\n# Complexity\n- Time complexity:\n<!-- Add your time complexity here, e.g. $$O(n)$$ -->\n\n- Space complexity:\n<!-- Add your space complexity here, e.g. $$O(n)$$ -->\n\n# Code\n```\nSELECT event_day "day", emp_id, SUM(out_time) - SUM(in_time) total_time\nFROM employees\nGROUP BY event_day, emp_id\n```
['PostgreSQL']