Done Sql4

Prb1 Seniors & Juniors

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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 ASC) AS RN FROM Candidates)
+
+SELECT 'Senior' AS experience, COUNT(employee_id) AS accepted_candidates FROM CTE WHERE experience = 'Senior' AND RN < 70000
+UNION
+SELECT 'Junior' AS experience, COUNT(employee_id) AS accepted_candidates FROM CTE WHERE experience = 'Junior' AND RN < (SELECT 70000 - IFNULL(MAX(RN),0) FROM CTE WHERE experience = 'Senior' AND RN < 70000)
+

Prb2 League Statistics

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+# Write your MySQL query statement below
+WITH CTE AS(
+    SELECT m1.home_team_id AS 'id', m1.home_team_goals AS 'hg',
+    m1.away_team_goals AS 'ag' FROM Matches m1
+    UNION ALL
+    SELECT m2.away_team_id AS 'id', m2.away_team_goals AS 'hg',
+    m2.home_team_goals AS 'ag' FROM Matches m2
+)
+
+-- SELECT * FROM CTE
+SELECT a.team_name, COUNT(c.id) AS 'matches_played', SUM(
+    CASE
+        WHEN c.hg > c.ag THEN 3
+        WHEN c.hg = c.ag THEN 1
+        ELSE 0
+    END
+) AS 'points', SUM(c.hg) AS 'goal_for', SUM(c.ag) AS 'goal_against',
+SUM(c.hg) - SUM(c.ag) AS 'goal_diff' 
+FROM Teams a LEFT JOIN CTE c ON a.team_id = c.id GROUP BY c.id
+ORDER BY points DESC, goal_diff DESC, a.team_name

Prb3

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+# Write your MySQL query statement below
+select s.name
+from SalesPerson s
+where s.name not in
+    (select s.name
+    from SalesPerson s
+        left join Orders o on s.sales_id = o.sales_id
+        left join Company c on o.com_id = c.com_id
+    where c.name = 'Red')

Prb4 Friend Request

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+# Write your MySQL query statement below
+with base as(select requester_id id from RequestAccepted
+union all
+select accepter_id id from RequestAccepted)
+
+
+select id, count(*) num  from base group by 1 order by 2 desc limit 1