608. Tree Node

https://leetcode.com/problems/tree-node/

Tree Node - LeetCode

select id, 
    case when p_id is null then 'Root' 
        when id in (select distinct p_id from Tree) then 'Inner'
        else 'Leaf' end as type
from Tree;

best

select
id, IF(ISNULL(p_id), 'Root', 
       IF(id in (SELECT p_id from tree),'Inner', 'Leaf')) as Type
from Tree