Sql2

Problem 1 : Rank Scores (https://leetcode.com/problems/rank-scores/ )

Problem 2 : Exchange Seats (https://leetcode.com/problems/exchange-seats/ )

Problem 3 : Tree Node (https://leetcode.com/problems/tree-node/ )

Problem 4 : Deparment Top 3 Salaries (https://leetcode.com/problems/department-top-three-salaries/ )