Completed Sql2

problem1.sql

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+# Write your MySQL query statement below
+SELECT s1.score, (
+    SELECT COUNT(DISTINCT s2.score)
+    FROM Scores s2
+    WHERE s2.score >= s1.score
+) AS 'rank' FROM Scores s1
+ORDER BY s1.score DESC;

problem2.sql

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+# Write your MySQL query statement below
+SELECT 
+    CASE WHEN id % 2 = 0 THEN id - 1
+         WHEN id % 2 = 1 AND id + 1 <= (SELECT MAX(id) FROM Seat) THEN id + 1
+         ELSE id
+    END AS id,
+    student
+FROM Seat
+ORDER BY id;

problem3.sql

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+# Write your MySQL query statement below
+SELECT id,
+CASE 
+    WHEN p_id IS null THEN 'Root'
+    WHEN id IN (SELECT p_id FROM Tree WHERE p_id IS NOT NULL) THEN 'Inner'
+    ELSE 'Leaf'
+END AS 'type'
+FROM Tree;

problem4.sql

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+# Write your MySQL query statement below
+WITH RankedSalaries 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 salary_rank
+    FROM Department d
+    JOIN Employee e
+    ON d.id = e.departmentId)
+SELECT Department, Employee, Salary
+FROM RankedSalaries
+WHERE salary_rank <= 3;