🔗 문제 링크https://leetcode.com/problems/analyze-organization-hierarchy/description/ 🔓 문제 풀이WITH RECURSIVE orgChart AS ( -- 재귀 쿼리 초기문(manager_id가 없는 값=ceo) SELECT employee_id, employee_name, manager_id, salary, department, 1 AS level, CAST(employee_id AS CHAR) AS org_order FROM Employees WHERE manager_id IS NULL UNION ALL ..

🔗 문제 링크https://leetcode.com/problems/human-traffic-of-stadium/description/ 🔓 문제 풀이풀이1>WITH get_previous AS ( SELECT id, visit_date, people, LAG(id) OVER (ORDER BY id) AS previous_id FROM Stadium WHERE people >= 100),get_diff_id AS ( SELECT id, visit_date, people, previous_id, IF(id - previous_id = 1, 0, 1) AS dif..

🔗 문제 링크https://leetcode.com/problems/trips-and-users/description/  🔓 문제 풀이풀이1>SELECT t.request_at AS 'Day', ROUND( SUM( CASE WHEN t.status IN ('cancelled_by_driver', 'cancelled_by_client') AND u1.banned = 'No' AND u2.banned = 'No' THEN 1 ELSE 0 END ) / NU..

🔗 문제 링크https://leetcode.com/problems/find-invalid-ip-addresses/description/ 🔓 문제 풀이select ip,count(*) as invalid_countfrom logswhere (substring_index(ip,".",1)>255or substring_index(substring_index(ip,".",2),".",-1) >255or substring_index(substring_index(ip,".",3),".",-1) >255or substring_index(substring_index(ip,".",4),".",-1) >255)or(left(substring_index(ip,".",1),1)=0or left(substring_index..

🔗 문제 링크https://leetcode.com/problems/department-top-three-salaries/description/?envType=study-plan-v2&envId=top-sql-50 🔓 문제 풀이WITH tb AS ( SELECT d.name AS Department, e.name AS Employee, e.id, DENSE_RANK() OVER (PARTITION BY e.departmentId ORDER BY e.Salary DESC) AS rank_salary FROM Employee e JOIN Department d ON e.departmentId = d.id)SEL..

🔒 문제CREATE TABLE employees ( employee_id INT PRIMARY KEY, first_name VARCHAR(50), last_name VARCHAR(50), hire_date DATE, manager_id INT, -- 상사의 employee_id (NULL이면 최고 관리자) department VARCHAR(50) -- 부서);-- 직원 데이터 삽입INSERT INTO employees (employee_id, first_name, last_name, hire_date, manager_id, department) VALUES(1, 'John', 'Doe', '2020-01-01', NULL, 'HR'), -- 최고 관리자 (상..