Completed Sql2

Department Top 3 Salaries.sql

@@ -0,0 +1,5 @@
+WITH CTE AS(
+
+    SELECT d.name AS 'Department', e.name AS 'Employee', e.salary AS 'Salary', DENSE_RANK() OVER(PARTITION BY e.departmentID ORDER BY e.salary DESC) as 'rnk' FROM Employee e LEFT JOIN Department d ON e.departmentID = d.id
+) 
+SELECT Department, Employee, Salary FROM CTE WHERE rnk <= 3

Exchange Seats.sql

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+SELECT (
+    CASE
+        WHEN MOD(id, 2) != 0 AND id = cnts THEN id
+        WHEN MOD(id, 2) != 0 THEN id + 1
+        ELSE id - 1
+    END
+) AS 'id', student FROM Seat, (SELECT COUNT(id) as 'cnts' FROM Seat) AS Seat_Counts ORDER BY id;

Rank Scores.sql

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+SELECT score, DENSE_RANK() OVER(ORDER BY score DESC) AS 'rank' FROM Scores;

Tree Node.sql

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+SELECT id, 'Root' AS type FROM Tree WHERE p_id IS null
+UNION
+SELECT id, 'Inner' AS type FROM Tree WHERE id IN (SELECT DISTINCT p_id FROM Tree WHERE p_id IS NOT NULL) AND p_id IS NOT NULL
+UNION
+SELECT id, 'Leaf' AS type FROM Tree WHERE id NOT IN (SELECT DISTINCT p_id FROM Tree WHERE p_id IS NOT NULL) AND p_id IS NOT NULL