diff --git a/Department Top 3 Salaries.sql b/Department Top 3 Salaries.sql
new file mode 100644
index 0000000..72260e1
--- /dev/null
+++ b/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
\ No newline at end of file
diff --git a/Exchange Seats.sql b/Exchange Seats.sql
new file mode 100644
index 0000000..873deff
--- /dev/null
+++ b/Exchange Seats.sql	
@@ -0,0 +1,7 @@
+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;
\ No newline at end of file
diff --git a/Rank Scores.sql b/Rank Scores.sql
new file mode 100644
index 0000000..fdf1eec
--- /dev/null
+++ b/Rank Scores.sql	
@@ -0,0 +1 @@
+SELECT score, DENSE_RANK() OVER(ORDER BY score DESC) AS 'rank' FROM Scores;
\ No newline at end of file
diff --git a/Tree Node.sql b/Tree Node.sql
new file mode 100644
index 0000000..6f78716
--- /dev/null
+++ b/Tree Node.sql	
@@ -0,0 +1,5 @@
+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