SQL2 Completed_RN32

Department Top Three Salaries

@@ -0,0 +1,13 @@
+WITH top_sal AS (
+    SELECT  DISTINCT departmentid,
+            (CASE WHEN DENSE_RANK() OVER(PARTITION BY departmentid ORDER BY salary DESC) <= 3 THEN salary END) top_3_sal
+    FROM employee
+)
+SELECT  DISTINCT d.name AS department,
+        e.name AS employee,
+        e.salary
+FROM employee e
+LEFT JOIN department d
+ON e.departmentid = d.id
+INNER JOIN top_sal t
+ON e.departmentid = t.departmentid AND e.salary = t.top_3_sal AND t.top_3_sal IS NOT NULL

Exhange Seats

@@ -0,0 +1,7 @@
+SELECT  id,
+        (CASE
+            WHEN id%2 = 0 THEN COALESCE(LAG(student,1) OVER(ORDER BY id), student)
+            WHEN id%2 = 1 THEN COALESCE(LEAD(student,1) OVER(ORDER BY id), student)
+        END) AS student
+FROM seat
+ORDER BY id

README.md

@@ -7,3 +7,5 @@ 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/ )
+
+Solutions provided in 4 different SQL files in repository

Rank Scores

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+SELECT  score,
+        DENSE_RANK() OVER(ORDER BY score DESC) rank
+FROM scores
+ORDER BY rank

Tree Node

@@ -0,0 +1,7 @@
+SELECT  id,
+        (CASE
+            WHEN p_id IS NULL THEN 'Root'
+            WHEN id IN (SELECT DISTINCT p_id FROM tree WHERE p_id IS NOT NULL) THEN 'Inner'
+            WHEN id NOT IN (SELECT DISTINCT p_id FROM tree WHERE p_id IS NOT NULL) THEN 'Leaf'
+        END) AS type
+FROM tree