Completed Q2_Sql1 Homework

Q1_Solution.sql

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

Q1_Solution_UsingDECLARE_SET

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+CREATE FUNCTION GetNthHighestSalary(N INT) RETURNS INT
+BEGIN
+    DECLARE M INT 
+    SET M = N-1
+    RETURN 
+    (
+        select 
+            distinct salary
+        from 
+            Employee
+        order by desc
+        limit M, 1
+    );
+    END

Q3_Sql1_solution.sql

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+with ranked_emails as 
+(
+    select 
+        id
+        , email
+        , row_number() over(partition by email order by id) as rnk
+    from 
+        Person
+)
+delete 
+from person p
+where p.id in (select ranked_emails.id from ranked_emails where rnk > 1)

SQL1_Q2_Question.sql

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+CREATE FUNCTION getNthHighestSalary(N INT) RETURNS INT
+BEGIN
+  RETURN (
+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

sql1_q3_crossjoin

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+DELETE p1 
+from person p1 
+cross join person p2 where p1.email = p2.email
+and p1.id > p2.id