Sql1 solution for Big Countries & Nth Highest Salary

README.md

@@ -1,5 +1,34 @@
 # 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 (
+      with cte as(select id, salary, DENSE_RANK()
+      OVER (ORDER BY salary DESC) AS dns_rnk
+      FROM Employee)
+
+      SELECT DISTINCT IFNULL(salary, null)
+      FROM cte
+      WHERE dns_rnk = N
+
+  );
+END
+
 3. Problem 3: Delete Duplicate Emails (https://leetcode.com/problems/delete-duplicate-emails/)
+Solution:
+
+DELETE P1 
+FROM Person P1
+JOIN Person P2
+Where P1.email = P2.email AND P1.id > P2.id