Done SQL4

FriendRequestsII.sql

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+WITH CTE AS (
+    SELECT requester_id AS id, 
+           (SELECT COUNT(*) FROM RequestAccepted WHERE id = requester_id OR id = accepter_id) AS num
+    FROM RequestAccepted
+
+    UNION
+
+    SELECT accepter_id AS id, 
+           (SELECT COUNT(*) FROM RequestAccepted WHERE id = requester_id OR id = accepter_id) AS num
+    FROM RequestAccepted
+)
+
+SELECT * 
+FROM CTE 
+ORDER BY num DESC 
+LIMIT 1;

LeagueStatistics.sql

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+WITH CTE AS (
+    SELECT home_team_id AS r1, away_team_id AS r2, home_team_goals AS g1, away_team_goals AS g2
+    FROM Matches
+    UNION ALL
+    SELECT away_team_id AS r1, home_team_id AS r2, away_team_goals AS g1, home_team_goals AS g2
+    FROM Matches
+)
+
+SELECT 
+    t.team_name,
+    COUNT(c.r1) AS matches_played,
+    SUM(
+        CASE 
+            WHEN c.g1 > c.g2 THEN 3
+            WHEN c.g1 = c.g2 THEN 1
+            ELSE 0
+        END
+    ) AS points,
+    SUM(c.g1) AS goal_for,
+    SUM(c.g2) AS goal_against,
+    SUM(c.g1 - c.g2) AS goal_diff
+FROM Teams t
+JOIN CTE c ON t.team_id = c.r1
+GROUP BY c.r1, t.team_name
+ORDER BY points DESC, goal_diff DESC, t.team_name;

SalesPerson.sql

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+WITH CTE AS (
+    SELECT o.sales_id
+    FROM Orders o
+    JOIN Company c ON o.com_id = c.com_id
+    WHERE c.name = 'RED'
+)
+
+SELECT name
+FROM SalesPerson
+WHERE sales_id NOT IN (SELECT sales_id FROM CTE);

number-of-seniors-and-juniors-to-join-the-company.sql

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+# Write your MySQL query statement below
+WITH CTE AS (
+    SELECT 
+        employee_id, experience, SUM(salary) OVER(PARTITION BY experience ORDER BY salary, employee_id) AS rsum 
+    FROM candidates
+)
+
+SELECT 
+    'Senior' AS experience, COUNT(employee_id) AS accepted_candidates 
+FROM CTE 
+WHERE experience = 'Senior' 
+  AND rsum <= 70000
+
+UNION
+
+SELECT 
+    'Junior' AS experience, COUNT(employee_id) AS accepted_candidates 
+FROM CTE 
+WHERE experience = 'Junior' 
+  AND rsum <= (
+      SELECT 70000 - IFNULL(MAX(rsum), 0) 
+      FROM CTE 
+      WHERE experience = 'Senior' 
+        AND rsum <= 70000
+  );