Completed Sql5

Problem1_ContiguousDate.sql

@@ -0,0 +1,17 @@
+# 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 
+select success_date  as 'dat','succeeded' as period_state,
+rank() over(order by success_date) as rnk
+from Succeeded
+where year(success_date)=2019
+order by dat)
+
+select period_state,min(dat) as start_date,
+max(dat) as end_date
+from (select *, rank() over(order by dat)-rnk as 'diff' from cte) as Y
+group by diff, period_state
+order by start_date;

Problem2_StudentReportByGeography.sql

@@ -0,0 +1,30 @@
+# Write your MySQL query statement below
+--Solution 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
+
+--Solution 2 with session variables
+
+select America,Asia,Europe from (
+    (select @am:=0, @as:=0,@eu:=0)t1,
+    (select @as:=@as+1 as 'asrnk',name as 'Asia' from student where continent='Asia' order by Asia)t2
+    right join 
+    (select @am:=@am+1 as 'amrnk',name as 'America' from student where continent='America' order by America)t3 on asrnk=amrnk
+    left join
+    (select @eu:=@eu+1 as 'eurnk',name as 'Europe' from student where continent='Europe' order by Europe)t4 on eurnk=amrnk
+)

Problem3_AvgSalarDepComp.sql

@@ -0,0 +1,19 @@
+# Write your MySQL query statement below
+with compavgcte as (
+select concat(year(pay_date),'-',lpad(month(pay_date),2,'0')) as pay_month,
+avg(amount) as compavg
+from salary
+group by 1),
+depavgcte as (select e.department_id,
+concat(year(pay_date),'-',lpad(month(pay_date),2,'0')) as pay_month,
+avg(amount) as depavg
+from employee e 
+inner join salary s on e.employee_id=s.employee_id
+group by 1,2)
+
+select d.pay_month,
+d.department_id,
+case when d.depavg > c.compavg then 'higher'
+     when d.depavg = c.compavg then 'same'
+     else 'lower' end as comparison
+from depavgcte d inner join compavgcte c on d.pay_month=c.pay_month

Problem4_GamePlay1.sql

@@ -0,0 +1,4 @@
+# Write your MySQL query statement below
+select player_id, min(event_date) as first_login
+from activity
+group by player_id