Done SQL 5

Average_Salary_Department_vs_Company.sql

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+SELECT 
+    ds.pay_month,
+    ds.department_id,
+    CASE
+        WHEN ds.department_avg > cs.company_avg THEN 'higher'
+        WHEN ds.department_avg < cs.company_avg THEN 'lower'
+        ELSE 'same'
+    END AS comparison
+FROM (
+    -- Calculate average salary per department per month
+    SELECT 
+        e.department_id,
+        DATE_FORMAT(s.pay_date, '%Y-%m') AS pay_month,
+        AVG(s.amount) AS department_avg
+    FROM 
+        salary s
+    JOIN 
+        employee e ON s.employee_id = e.employee_id
+    GROUP BY 
+        e.department_id, DATE_FORMAT(s.pay_date, '%Y-%m')
+) AS ds
+JOIN (
+    -- Calculate company-wide average salary per month
+    SELECT 
+        DATE_FORMAT(pay_date, '%Y-%m') AS pay_month,
+        AVG(amount) AS company_avg
+    FROM 
+        salary
+    GROUP BY 
+        DATE_FORMAT(pay_date, '%Y-%m')
+) AS cs
+ON 
+    ds.pay_month = cs.pay_month;

Game_Play_Analysis_I.sql

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+# Write your MySQL query statement below
+SELECT A.player_id, MIN(A.event_date) AS first_login
+FROM Activity A GROUP By A.player_id;

Report_Contiguos_Dates.sql

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+# Write your MySQL query statement below
+WITH combined_status AS (
+
+    SELECT 
+        fail_date AS dat, 
+        'failed' AS period_state
+    FROM 
+        Failed
+    WHERE 
+        YEAR(fail_date) = 2019
+
+    UNION ALL
+
+    SELECT 
+        success_date AS dat, 
+        'succeeded' AS period_state
+    FROM 
+        Succeeded
+    WHERE 
+        YEAR(success_date) = 2019
+),
+ranked_status AS (
+
+    SELECT 
+        dat,
+        period_state,
+        ROW_NUMBER() OVER (ORDER BY dat) AS row_num,
+        RANK() OVER (PARTITION BY period_state ORDER BY dat) AS state_rank
+    FROM 
+        combined_status
+),
+grouped_status AS (
+    -- Use the difference between row_num and state_rank as grouping key
+    SELECT 
+        dat,
+        period_state,
+        ROW_NUMBER() OVER (ORDER BY dat) - RANK() OVER (PARTITION BY period_state ORDER BY dat) AS grp
+    FROM 
+        combined_status
+)
+
+SELECT 
+    period_state,
+    MIN(dat) AS start_date,
+    MAX(dat) AS end_date
+FROM 
+    grouped_status
+GROUP BY 
+    period_state, grp
+ORDER BY 
+    start_date;

Student_Report_By_Geography.sql

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+WITH first as(
+    SELECT name as 'America', ROW_NUMBER() OVER(ORDER BY name) AS 'rnk' From student WHERE continent = 'America'
+),
+second as(
+    SELECT name as 'Asia', ROW_NUMBER() OVER(ORDER BY name) AS 'rnk' From student WHERE continent = 'Asia'
+),
+third as(
+    SELECT name as 'Europe', ROW_NUMBER() OVER(ORDER BY name) AS 'rnk' From student WHERE continent = 'Europe'
+)
+
+SELECT America , Asia , Europe FROM second RIGHT JOIN first on first.rnk = second.rnk LEFT JOIN third 
+ON first.rnk = third.rnk;