diff --git a/Problem1_RankScores.sql b/Problem1_RankScores.sql
new file mode 100644
index 0000000..e5d75ac
--- /dev/null
+++ b/Problem1_RankScores.sql
@@ -0,0 +1,4 @@
+# Write your MySQL query statement below
+select score, dense_rank() over (order by score desc) as 'rank'
+from Scores
+order by score desc;
\ No newline at end of file
diff --git a/Problem2_ExchangeSeats.sql b/Problem2_ExchangeSeats.sql
new file mode 100644
index 0000000..1da441d
--- /dev/null
+++ b/Problem2_ExchangeSeats.sql
@@ -0,0 +1,9 @@
+# Write your MySQL query statement below
+select 
+case when id = (select max(id) from seat) and id %2 != 0 then id
+     when id % 2=0 then id-1
+     else id+1 
+END as id,
+student 
+from seat
+order by id;
\ No newline at end of file
diff --git a/Problem3_TreeNode.sql b/Problem3_TreeNode.sql
new file mode 100644
index 0000000..924b4a4
--- /dev/null
+++ b/Problem3_TreeNode.sql
@@ -0,0 +1,15 @@
+# Write your MySQL query statement below
+
+select 
+id,
+case when p_id is null then 'Root'
+     when id in (select distinct p_id from Tree) then 'Inner'
+     else 'Leaf' end as type
+from Tree;
+ 
+#Using if condition
+ 
+select
+id,
+if(p_id is null,'Root',if(id in (select distinct p_id from Tree),'Inner','Leaf')) as type
+from Tree;
diff --git a/Problem4_DeptTop3Salaries.sql b/Problem4_DeptTop3Salaries.sql
new file mode 100644
index 0000000..344c75d
--- /dev/null
+++ b/Problem4_DeptTop3Salaries.sql
@@ -0,0 +1,10 @@
+# Write your MySQL query statement below
+select A.department,A.employee,A.salary
+from
+(select d.name as department,
+e.name as employee,
+e.salary,
+dense_rank() over(partition by e.departmentId order by e.salary desc) as salaryrank
+from department d
+inner join employee e on d.id=e.departmentId) A
+where salaryrank <=3