adding sql problems

Author: shreyashji

36.29 How to find all levels of Employee Manager Hierarchy Recursion.sql

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+#How to find all levels of Employee Manager Hierarchy | Recursion
+#manager id is null then he is the top most manager in orgz
+#create table emmp(emp_id int,emp_name varchar(20),department_id int,manager_id int);
+select * from emmp;
+#insert into emmp values(1,'Adam Owens',103,3);
+#insert into emmp values(2,'Smith Jones',102,5);
+#insert into emmp values(3,'Hilary Riles',101,4);
+#insert into emmp values(4,'Richard Robinson',103,3);
+#insert into emmp values(5,'Samuel Pitt',103,3);
+#insert into emmp values(6,'Mark Miles',null,7);
+#insert into emmp values(7,'Jenny Jeff',999,null);
+
+#name of the immediate manager
+select emp.emp_name as EmployeeName, mgr.emp_name as ManagerName  from emmp emp
+inner join emmp mgr 
+on emp.Manager_id=mgr.emp_id ;
+
+with EmpMgrCTE
+AS(
+Select emp_id,emp_name,manager_id,0 as EmpLevel from emmp
+where manager_id is null
+union all
+Select EMPP.emp_id,EMPP.emp_name,EMPP.manager_id,mngr.EmpLevel+1
+from emmp EMPP
+INNER JOIN EmpMgrCTE AS mngr
+on empp.Manager_id = mngr.emp_id
+)
+select * from EmpMgrCTE 
+order by EmpLevel;

36.30 SQL Query to find a leap year 2 methods.sql

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+#SQL Query to find a leap year | 2 methods
+#leap year
+#year divisible by 4 but not by 100
+#year divissible by 400
+#select cast(@year as char(4))+'0229'  this will give  20210229
+
+declare @year int = 2021;
+select cast(@year as char(4))+'0229' ;
+#CHECK IF DATE IS VALID 0 NOT VALID
+declare @year int = 2021;
+select ISDATE(cast(@year as char(4) ) +'0229');
+
+#FINAL
+declare @year int = 2021;
+select CASE WHEN  ISDATE(cast(@year as char(4) ) +'0229') = 1
+THEN 'LEAP YEAR'
+ELSE 'NOT A LEAP YEAR'
+END
+
+#ANOTHER WAY
+declare @year int = 2020;
+SELECT case when (@year % 4 = 0 and @year % 100<>0) or @year % 400 = 0 
+THEN 'LEAP YEAR'
+ELSE 'NOT A LEAP YEAR'
+END

36.31 How to generate date records for a Calendar table.sql

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+#How to generate date records for a Calendar table
+
+declare @startdate date = '2020-01-01';
+declare @enddate date = '2020-12-31';
+
+with cte_calender as (
+select @startdate as [date]
+union all
+select DATEADD(DD,1,[date])
+FROM cte_calender
+where DATEADD(DD,1,[date]) <= @enddate )
+select [date] from  cte_calender
+OPTION (MAXRECURSION 400);

36.32 What is the difference between Translate and Replace.sql

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+#What is the difference between Translate and Replace
+
+#TRANSLATE(INPUT,CHARACTER,TRANSLATIONS) -works by replacing char,repalce char,need to specify equal no. of characters
+#replace (string_expression,string_pattern,string_replacement) -replaces entire string,replace string,can also replace a string of varying length
+select TRANSLATE('xxx1234567891zzz','123456789','abcdefghi');
+#1-a,2-b,3-c,4-d,e-5,f-6,g-7,h-8,i-9,1-a
+select replace('1234567891','123456789','abcdefghi');
+
+select replace('1234567891','123456789','a');

38. Amazon Prime Subscription Rate SQL Logic.sql

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+#create table userss (user_id integer,name varchar(20),join_date date);
+#insert into userss values (1, 'Jon','2020-02-14'), (2, 'Jane', '2020-02-14'), (3, 'Jill','2020-02-15' ), (4, 'Josh','2020-02-15'), (5, 'Jean','2020-02-16'), (6, 'Justin','2020-02-17'),(7, 'Jeremy', '2020-02-18');
+select * from  userss;
+#delete from userss;
+#create table events(user_id integer,type varchar(10),access_date date);
+#insert into events values (1, 'Pay', '2020-03-01'), (2, 'Music', '2020-03-02'), (2, 'P', '2020-03-12'),(3, 'Music', '2020-03-15'), (4, 'Music','2020-03-15'), (1, 'P', '2020-03-16'), (3, 'P', '2020-03-22');
+
+select * from  userss;
+select * from  events;
+#Given the following two tables, return the fraction of users, rounded to two decimal places,
+#who accessed Amazon music and upgraded to prime membership within the first 30 days of signing up. 
+#p stands for when user purchase prime membership
+#10 users,5 access amazon music,only 2 purchase prime membership ,ratio 2 divide by 5 =40%
+
+#find who access amazon music
+select * from userss
+where user_id in (select user_id from events where type='Music');
+#out of this i have to check how many have subscibed to amazon prime within 30 dyas of joining date
+#need access date when they converted there membership to prime membership
+#left join there woulb be users who did not join prime membership
+select u.*,e.type,e.access_date from userss u 
+left join events  e on u.user_id=e.user_id and e.type='P'
+where u.user_id in (select user_id from events where type='Music');
+
+#calculate the difference also
+select u.*,e.type,e.access_date,datediff(day,u.join_date,e.access_date) as no_of_days from userss u 
+left join events  e on u.user_id=e.user_id and e.type='P'
+where u.user_id in (select user_id from events where type='Music');
+
+#
+#CASE When datediff(day,u.join_date,e.access_date) <=30 then user_id -->who bought in 30 days  taking user_id 
+
+select #u.*,e.type,e.access_date,datediff(day,u.join_date,e.access_date) as no_of_days from userss u 
+count(distinct u.user_id) as total_users,count(distinct CASE When datediff(day,u.join_date,e.access_date) <=30 then user_id end)
+,1.0*count(distinct CASE When datediff(day,u.join_date,e.access_date) <=30 then user_id end) / count(distinct u.user_id) * 100
+from userss u 
+left join events  e on u.user_id=e.user_id and e.type='P'
+where u.user_id in (select user_id from events where type='Music')
+