Complete SQL2

DepartmentTopThreeSalaries.sql

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+WITH ranks AS (
+  SELECT
+    d.name AS department,
+    e.name AS employee,
+    e.salary,
+    DENSE_RANK() OVER(PARTITION BY d.id ORDER BY e.salary DESC) AS salary_rank
+  FROM employee e
+  JOIN department d
+    ON d.id = e.departmentId
+)
+SELECT
+  department,
+  employee,
+  salary
+FROM ranks
+WHERE salary_rank <= 3;

ExchangeSeat.sql

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+SELECT s1.id, COALESCE(s2.student , s1.student) AS 'student' FROM seat s1 LEFT JOIN seat s2 
+ON (s1.id +1) ^ 1 - 1 = s2.id ORDER BY s1.id;

RankScore.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;

TreeNode.sql

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+SELECT id , IF(
+    ISNULL(p_id) , 'Root' , IF(id IN (SELECT DISTINCT p_id from tree) , 'Inner' , 'Leaf')
+
+) AS 'type' from tree;