SQL2 submitted

Department_top3_Salaries.sql

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+WITH CTE as(
+    SELECT d.name as 'department',d.id as'did', e.name as 'employee', e.salary as 'salary' from employee e left join department d ON e.departmentId = d.id
+)
+SELECT department, employee, salary from CTE c
+where 3> (Select count(DISTINCT e2.salary)from employee e2 where c.did = e2.departmentId and e2.salary>c.salary)

ExchangeSeats.sql

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+SELECT(
+    CASE
+    WHEN MOD(id,2) !=0 AND id = cnts THEN id
+    WHEN MOD(id,2) !=0 AND id !=cnts THEN id+1
+    ELSE id-1
+    END
+) as 'id', student from seat,
+(SELECT COUNT(*) AS 'cnts' from seat) as seat_counts
+ORDER BY id

RankScores.sql

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+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, 'Root' as type from tree where p_id is 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
+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
+Order by id