Completed Sql1

Problem 1.sql

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+select name, population, area from World
+where area >= 3000000 or population >= 25000000;

Problem 2.sql

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+CREATE FUNCTION getNthHighestSalary(N INT) RETURNS INT
+BEGIN
+  RETURN (
+      # Write your MySQL query statement below.
+    with cte as (
+        select *, dense_rank() over (order by salary desc) as rnk from Employee
+    )
+    select distinct ifnull(salary, null) from cte where rnk = N
+  );
+END

Problem 3.sql

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+delete p1 from Person p1 cross join Person p2
+where p1.email = p2.email and p1.id > p2.id