done Sql5

AvdDepSalVSComSal.sql

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+# Approach 1:
+
+Select departmentSalary.pay_month, department_id, (
+Case 
+When department_avg>company_avg then “higher”
+When department_avg<company_avg then “lower”
+else 
+“same”
+End) as Comparison from (Select date_format(pay_date, ‘%y-%m’) as pay_month, department_id, avg(amount) as department_avg from Salary join Employee on salary.employee_id=employee.employee_id group by department_id,pay_month) as departmentSalary  join 
+(Select date_format(Pay_date, ‘%y-%m’) as pay_month, avg(amount) as company_avg from salary group by pay_month) as companySalary on departmentSalary.pay_month=companySalary.pay_month;
+
+
+# Approach 2: 
+
+With departmentSalary as(
+ Select date_format(pay_date, ‘%y-%m’) as pay_month, department_id, avg(amount) as department_avg from Salary join Employee on salary.employee_id=employee.employee_id group by department_id,pay_month) , 
+companySalary as(
+Select date_format(Pay_date, ‘%y-%m’) as pay_month, avg(amount) as company_avg from salary group by pay_month)
+
+Select departmentSalary.pay_month, department_id, (
+Case 
+When department_avg>company_avg then “higher”
+When department_avg<company_avg then “lower”
+else 
+“same”
+End) as Comparison from departmentSalary join companySalary on departmentSalary.pay_month=companySalary.pay_month;
+

GamePlayAnalysis1.sql

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+# Approach 1:
+SELECT player_id, MIN(event_date) AS first_login FROM Activity GROUP BY player_id;
+
+
+# Approach 2: 
+SELECT 
+    player_id, 
+    event_date AS first_login 
+FROM (
+    SELECT 
+        player_id, 
+        event_date, 
+        RANK() OVER (PARTITION BY player_id ORDER BY event_date ASC) AS rnk 
+    FROM Activity
+) subquery
+WHERE rnk = 1;
+
+
+# Approach 3:
+SELECT DISTINCT 
+    player_id, 
+    FIRST_VALUE(event_date) OVER (PARTITION BY player_id ORDER BY event_date ASC) AS first_login 
+FROM Activity;
+
+
+# Approach 4: 
+SELECT DISTINCT 
+    player_id, 
+    LAST_VALUE(event_date) OVER (PARTITION BY player_id ORDER BY event_date ASC ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS first_login 
+FROM Activity;

Report_contiguos.sql

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+#Approach 1:
+
+WITH CTE AS (
+    SELECT fail_date AS dat, 
+           'failed' AS period_state, 
+           RANK() OVER (ORDER BY fail_date) AS rnk 
+    FROM failed 
+    WHERE YEAR(fail_date) = 2019
+    UNION ALL
+    SELECT success_date AS dat, 
+           'succeeded' AS period_state, 
+           RANK() OVER (ORDER BY success_date) AS rnk 
+    FROM succeeded 
+    WHERE YEAR(success_date) = 2019
+)
+
+SELECT period_state, 
+       MIN(dat) AS start_date, 
+       MAX(dat) AS end_date 
+FROM (
+    SELECT *, 
+           RANK() OVER (ORDER BY dat) - rnk AS group_rnk 
+    FROM CTE
+) AS grouped_cte
+GROUP BY group_rnk, period_state 
+ORDER BY 2;
+

StudentReportByGeo.sql

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+# Approach 1: 
+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;
+
+
+# Approach 2: 
+SELECT @as := @as + 1 AS asrank, name AS Asia 
+FROM student 
+WHERE continent = 'Asia' 
+ORDER BY name;
+
+SELECT @am := @am + 1 AS amrank, name AS America 
+FROM student 
+WHERE continent = 'America' 
+ORDER BY name;
+
+SELECT @eu := @eu + 1 AS eurank, name AS Europe 
+FROM student 
+WHERE continent = 'Europe' 
+ORDER BY name;
+
+SELECT America, Asia, Europe 
+FROM (
+    SELECT @as := @as + 1 AS asrank, name AS Asia 
+    FROM student 
+    WHERE continent = 'Asia' 
+    ORDER BY name
+) t1
+RIGHT JOIN (
+    SELECT @am := @am + 1 AS amrank, name AS America 
+    FROM student 
+    WHERE continent = 'America' 
+    ORDER BY name
+) t2
+ON asrank = amrank
+LEFT JOIN (
+    SELECT @eu := @eu + 1 AS eurank, name AS Europe 
+    FROM student 
+    WHERE continent = 'Europe' 
+    ORDER BY name
+) t3
+ON amrank = eurank;
+
+
+