Set 4 문제

Set 4 문제

 

 

Weather Observation Station 3

 

SELECT DISTINCT city
FROM station
WHERE MOD(id, 2) = 0;

 

 

Weather Observation Station 19

 

SELECT ROUND(SQRT(POWER(MAX(lat_n) - MIN(lat_n), 2) + POWER(MAX(long_w) - MIN(long_w), 2)), 4)
FROM station;

 

 

Placements

 

SELECT S.Name
FROM Students as S
LEFT JOIN Packages as P1 ON S.ID = P1.ID
LEFT JOIN Friends as F ON S.ID = F.ID
LEFT JOIN Packages as P2 ON F.Friend_ID = P2.ID
WHERE P1.Salary < P2.Salary
ORDER BY P2.Salary;

 

 

Binary Tree Nodes

 

SELECT DISTINCT BST1.N
     , CASE
            WHEN BST1.P IS NULL THEN 'Root'
            WHEN BST2.N IS NULL THEN 'Leaf'
            ELSE 'Inner'
       END
FROM BST AS BST1
LEFT JOIN BST AS BST2 ON BST1.N = BST2.P
ORDER BY BST1.N;