sql5 commit

AvgSalaryDepVsComp.sql

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+select comp.pay_month, dep.department_id,(
+case
+    when depsalary > compsalary then 'higher'
+    when depsalary < compsalary then 'lower'
+    else 'same' 
+end
+) as comparison from 
+(select date_format(pay_date,'%Y-%m') as 'pay_month' ,employee_id, avg(amount)as 'compsalary' 
+ from salary group by pay_month) as comp
+  join 
+  (select date_format(pay_date,'%Y-%m') as 'pay_month', e.department_id, avg(amount) as 'depsalary' 
+  from salary s join employee e on s.employee_id=e.employee_id group by e.department_id , pay_month) as dep
+  on  dep.pay_month = comp.pay_month;

GamePlayAnalysis1.sql

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+--Solution1
+select player_id , min(event_date) as 'first_login' from activity group by player_id
+
+--Solution2
+select distinct player_id, min(event_date) over(partition by player_id) as 'first_login' from activity;
+
+--Solution3
+select a.player_id, a.event_date as 'first_login' from ( select b.player_id, b.event_date, rank() over(partition by b.player_id order by b.event_date) as 'rnk' from activity b ) a where a.rnk = 1;
+
+--Solution4
+select distinct a.player_id , first_value(event_date) over(partition by a.player_id order by event_date) as 'first_login' from activity a
+
+--Solution5
+select distinct a.player_id , last_value(event_date) over(partition by a.player_id order by event_date desc 
+range between unbounded preceding and unbounded following) as 'first_login' from activity a

ReportContiguosDates.sql

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+# Write your MySQL query statement below
+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_rank' from cte) as y 
+    group by group_rank , period_state order by start_date;

StudentReportByGeography.sql

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+with cte as 
+    (select name as 'America', row_number() over (order by name) as 'rnk' from student 
+    where continent='America' order by name),
+
+cte1 as 
+    (select name as 'Asia', row_number() over (order by name) as 'rnk' from student 
+    where continent='Asia' order by name),
+
+cte2  as (select name as 'Europe', row_number() over (order by name) as 'rnk' from student 
+where continent='Europe' order by name)
+
+select America, Asia , Europe from cte1 
+    right join cte on cte.rnk=cte1.rnk 
+    left join cte2 on cte.rnk=cte2.rnk;