608: Solution with step by step explanation
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 t.id,\n    CASE\n        WHEN t.p_id IS NULL THEN \'Root\'\n        WHEN EXISTS (SELECT 1 FROM Tree WHERE p_id = t.id) THEN \'Inner\'\n        ELSE \'Leaf\'\n    END AS type\nFROM Tree t\n```
['Database', 'MySQL']