Sql1

1. Problem 1: Big Countries (https://leetcode.com/problems/big-countries/)

   --Solution

   SELECT name, population, area FROM world WHERE area >= 3000000 OR population >= 25000000;

2. Problem 2: Nth Highest Salary (https://leetcode.com/problems/nth-highest-salary/)

   --Solution

   CREATE FUNCTION getNthHighestSalary(N INT) RETURNS INT BEGIN RETURN ( # Write your MySQL query statement below. SELECT DISTINCT IFNULL(salary,null) FROM (SELECT salary, DENSE_RANK() OVER(ORDER BY salary DESC) AS rnk FROM employee ) a WHERE rnk = N ); END

3. Problem 3: Delete Duplicate Emails (https://leetcode.com/problems/delete-duplicate-emails/)

   --Solution

   DELETE FROM person WHERE id NOT IN
   (SELECT DISTINCT id FROM (SELECT id, email, ROW_NUMBER() OVER(PARTITION BY email ORDER BY id) rwn FROM person) a WHERE rwn = 1 );