SQL5 Done

averagesalary.sql

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+# Write your MySQL query statement below
+WITH
+    S AS (
+        SELECT *
+        FROM
+            Salary
+            JOIN Employee USING (employee_id)
+    ),
+    T AS (
+        SELECT
+            DATE_FORMAT(pay_date, '%Y-%m') AS pay_month,
+            department_id,
+            AVG(amount) OVER (PARTITION BY pay_date, department_id) AS department_avg,
+            AVG(amount) OVER (PARTITION BY pay_date) AS company_avg
+        FROM S
+    )
+SELECT
+    pay_month,
+    department_id,
+    CASE
+        WHEN AVG(department_avg) > AVG(company_avg) THEN 'higher'
+        WHEN AVG(department_avg) < AVG(company_avg) THEN 'lower'
+        ELSE 'same'
+    END AS comparison
+FROM T
+GROUP BY 1, 2;

gameplayanalysis1.sql

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+SELECT player_id, MIN(event_date) AS first_login
+FROM Activity
+GROUP BY 1;
+
+

reportcontiguous.sql

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+# Write your MySQL query statement below
+WITH
+    T AS (
+        SELECT fail_date AS dt, 'failed' AS st
+        FROM Failed
+        WHERE YEAR(fail_date) = 2019
+        UNION ALL
+        SELECT success_date AS dt, 'succeeded' AS st
+        FROM Succeeded
+        WHERE YEAR(success_date) = 2019
+    )
+SELECT
+    st AS period_state,
+    MIN(dt) AS start_date,
+    MAX(dt) AS end_date
+FROM
+    (
+        SELECT
+            *,
+            SUBDATE(
+                dt,
+                RANK() OVER (
+                    PARTITION BY st
+                    ORDER BY dt
+                )
+            ) AS pt
+        FROM T
+    ) AS t
+GROUP BY 1, pt
+ORDER BY 2;

studentreports.sql

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+# Write your MySQL query statement below
+WITH
+    T AS (
+        SELECT
+            *,
+            ROW_NUMBER() OVER (
+                PARTITION BY continent
+                ORDER BY name
+            ) AS rk
+        FROM Student
+    )
+SELECT
+    MAX(IF(continent = 'America', name, NULL)) AS 'America',
+    MAX(IF(continent = 'Asia', name, NULL)) AS 'Asia',
+    MAX(IF(continent = 'Europe', name, NULL)) AS 'Europe'
+FROM T
+GROUP BY rk;
+