HR-SQL Binary Tree Nodes

1 개요

HR-SQL Binary Tree Nodes

해커랭크 SQL

문제	DB2	MS SQL	MySQL	Oracle
HR-SQL Advanced Select e
HR-SQL Type of Triangle
HR-SQL The PADS
HR-SQL Occupations
HR-SQL Binary Tree Nodes
HR-SQL New Companies

4 MySQL

SELECT N, CASE
    WHEN P IS NULL THEN 'Root' 
    WHEN(SELECT COUNT(*) FROM BST WHERE P=A.N) > 0 THEN 'Inner'
    ELSE 'Leaf'
END
FROM BST A
ORDER BY N;