The below simplified query worked for me in mysql with cte as (select *, row_number() over (partition by username order by startdate) as rn, count(*) over (partition by username) as ct from useractivity) select * from cte where rn = case when ct = 1 then ct else ct - 1 end ;

I'm getting the same results by running the following: with cte as (select *, row_number() over (partition by username order by startdate) as rn, count(1) over (partition by username) as cnt from useractivity) select * from cte where cnt = 1 or rn = cnt - 1;

My solution with the script:- create table activity1( username varchar(20), acitivity varchar(20), startdate date, enddate date); insert into activity1 (username,acitivity,startdate,enddate) values ('Amy','Travel','2020-02-12','2020-02-20'), ('Amy','Dancing','2020-02-21','2020-02-23'), ('Amy','Travel','2020-02-24','2020-02-28'), ('Joe','Travel','2020-02-11','2020-02-18'), ('Adam','Travel','2020-02-12','2020-02-20'), ('Adam','Dancing','2020-02-21','2020-02-23'), ('Adam','Singing','2020-02-24','2020-02-28'), ('Adam','Travel','2020-03-01','2020-03-28'); with t1 as(select username,activity,startdate,enddate,row_number() over(partition by username order by enddate desc) sorted_date, count(enddate) over(partition by username) count from activity1) select username,activity,startdate,enddate from t1 where (sorted_date=2 and count >1) or (sorted_date=1 and count=1)

IT'S ALWAYS THE UNDERRATED VID THAT'S LEGIT! THANK YOU!

Genius as always. Thanks for sharing. Am sure u are overwhelmed with so many emails now. I am sure mine is missing in your inbox. Anyway love your videos. Wish you could locate my mail tho 😂😂😂. Keep it up and we love you

Same if we mention DESC in order by clause of row number & then replace 'cnt-1' to '2'

First Like... I'm eagerly waiting for your videos sir... Thanks 👍❤️

Thanks, TFQ and love you boss the way you explain the query and solve it's up to the mark ♥

My attempt with CTE and Window functions :- sample data: create table useractivity (username text, activity text, startdate date, enddate date); insert into useractivity values ('Amy','Travel','2020-02-12','2020-02-20'); insert into useractivity values ('Amy','Dancing','2020-02-21','2020-02-23'); insert into useractivity values ('Amy','Travel','2020-02-24','2020-02-28'); insert into useractivity values ('Joe','Travel','2020-02-11','2020-02-18'); insert into useractivity values ('Adam','Travel','2020-02-12','2020-02-20'); insert into useractivity values ('Adam','Dancing','2020-02-21','2020-02-23'); insert into useractivity values ('Adam','Singing','2020-02-24','2020-02-28'); insert into useractivity values ('Adam','Travel','2020-03-01','2020-03-28'); solution : with cte as (select *, rank() over (partition by username order by startdate desc) as rnk from useractivity), cte2 as (select username, activity, startdate, enddate, rank() over (partition by username order by startdate) as rnk from cte where rnk

I need to work a lot of similar problems so partition and case becomes second nature. This is a great tutorial

Hii, your video are more useful, so please upload video about the topics like cluster, and indexex, thnq

Thank you so much for sharing! In your solution, lines 4 & 5 could be simplified using: , COUNT(*) OVER(partition by username) AS cnt

with cte as ( select *, row_number() over(partition by username order by enddate) as rn, count(*) over(partition by username order by username) as cnt from activity1) select username,acitivity,startdate,enddate from cte where rn= case when cnt=1 then 1 else cnt-1 end

Thanks TFQ. Very helpful I have a basic question Leaving the rows with count =1 aside for now, would it be correct to sort the partition by DESCENDING order and then select the rows with row number rn=2 instead of the cnt-1?

Thanks T! heading to learn the frame clause next. I tried out using your logic just ordered the result by start date in descending order. with cte as (select * ,row_number() over (partition by username order by startdate desc) rn ,count(*) over (partition by username order by startdate desc range between unbounded preceding and unbounded following) cnt from useractivity order by username, startdate desc) select username, activity, startdate, enddate from cte where rn= case when rn=cnt then 1 else 2 end;

I don't understand why do we need to have count at all when the question concerns about activity and time sorting. We could just sort the data by start_date and use nth_value() to get the second most recent activity. My solution is below: with cte as ( select *, coalesce(nth_value(activity,2) over (partition by username order by start_date desc range between unbounded preceding and unbounded following),activity) as second_most_recent_activty from activity1) select username,activity,start_date,end_date from cte where activity=second_most_recent_activty; Coalesce is used because for Joe null will be returned as it has only one row.

Thank you thoufiq

Hello! This is my simple solution: With cte as(Select *, row_number()over(partition by username order by startdate desc) as rn,count(*)over(partition by username ) as total_count From User activity) Select username, activity, startdate,enddate From cte Where rn=2 or total_count=1

I think simplest one select username,activity,startdate,enddate from (select *, row_number() over(partition by username order by startdate desc) as rn from Useractivity) where rn=2 union select username,activity,startdate,enddate from Useractivity group by username having count(username)=1

Thank you so much this helped a lot!!!! You saved my life

sir a kind request is that always share a data set so that we can also practice it

Awesome mate👌🏻 God bless you

Hey man, It works great and without any problems.

It's not necessary to complicate the COUNT function with RANGE: partitioning by username is adequate. The following query is simpler: WITH activity_recency AS (SELECT *, ROW_NUMBER() OVER (PARTITION BY username ORDER BY startdate DESC) AS recency, COUNT(*) OVER (PARTITION BY username) AS activity_count FROM user_activity) SELECT username, activity, startdate, enddate FROM activity_recency WHERE recency = 2 OR activity_count = 1; This query can also easily be enhanced to return any nth most recent or the most recent activity if there aren't n activities.

Good to know about frame clause. Range one

easiest solution: with cte as (select *, row_number() over(partition by username order by startdate desc) rn, count() over(partition by username) as cnt from activity1) select * from cte where (rn=1 and cnt=1) or (rn=2 and cnt>1)

Really appreciate for your sharing. 👍

@TechTfq -I could see that you use window function effectively in most of the solutions. Just want to know if window function is good performancewise also... Thanks

Sir my solution in MySQL - select * from (SELECT uc.*, ROW_NUMBER() OVER(PARTITION BY username ORDER BY username,startDate) as row_count,count(*) OVER(PARTITION BY username) as total_count FROM `user_activity` uc) as x where x.row_count = 2 or (x.row_count = 1 and x.total_count = 1);

Thanks for sharing TFQ, The question says the table does not contain Primary Key! Does that mean there could be two person with same name, there could be different records for same name, eg there could be two differrent person named Amy? Do we need to cosider this as an edge case?

Thankyou very much sir for bringing this 🙏

Thank you, Thoufiq.

with t2 as(select username, activity, startdate, enddate from(select *, rank() over (partition by username order by enddate desc) as recency from useractivity u) t1 where recency=2), t3 as (select * from useractivity u where username not in (select username from t2)) select * from t2,t3

I feel this is straight forward.. Kindly let me know if this approach has any drawbacks.... with intr as (select *,count(*) over (partition by username ) as cnt, rank() over (partition by username order by startDate desc ) as rnk from UserActivity), flag as (select *, case when cnt =1 then 'valid' when rnk =2 then 'valid' else 'invalid' end as flg from intr) select * from flag where flg='valid'

thanks for sharing.. love from india

I'm getting the same results by running the following: if it's wrong, please let me know with cte as(select *,row_number() over(partition by username order by startdate desc) rn from activity1 qualify rn=2) select * exclude rn from cte union all select * from activity1 where username in (select username from activity1 group by username having count(*)=1);

Using rank instead of row_number select username, activity, startDate, endDate from (select *, case when max(rnk) over (partition by username) = 1 then 'x' when rnk = 2 then 'x' end as slct from (select *, rank() over (partition by username order by endDate desc) as rnk from UserActivity ) x ) y where y.slct is not null

Please add the Data set for the practice

hi , I think for windows function: row_number(), it should be-> order by end_date desc.

Thank you Tofiq, based on your explanation I can solve the problem as below, what do you think? Is it possible or? With cte_secondActivity As (Select *, row_number() over(partion by userName order by start date desc) as row_nr From user Activity) Select username, activity,startdate,start date, From cte_secondActivity Where row_nr=2

Very nice explanation

Respected sir I hope you are well .kinldy make a video for beginner to expert which course start for DB and which DBMS use. Which DBMS have a scope in future .plsease shear your experience in video .and tell step by step which course should first then second then third etc. And how we apply for job and which compney should apply through linked-in because each company required 2-3 year experiences.But we have don't experience. Kindly tell us a plate form or you tube channel link. Thanks a lot sir

have solved by : select * from ( select *, row_number()over(PARTITION by username order by endDate desc) as rn, count(*) over (PARTITION by username) as total_records from Table_1 ) where ( (rn = 1 and total_records =1) or (rn = 2 and total_records 1) )

Sharing an alternative! with cte as (select username,activity,startDate,endDate,rank() over(partition by username order by startDate desc) as rnk from user_activity), table1 as (select username,activity,startDate,endDate,rnk,max(rnk) over(partition by username) as max_rnk from cte) select username,activity,startDate,endDate from table1 where rnk = 2 or (max_rnk = 1)

Continue.....

Hello Thoufiq, Thanks for the video!! I have one question. In the problem statement it is written that a user cannot perform two activities at the same time. Suppose if table contains records with overlapping time periods, shouldn't that condition be checked as well and those records be discarded? Thanks Kamal

VERY INTERESTING

Fast download, thank you brother))

@techtfq,, why dont we use u this way based on rowid,,, select * from (select username,activity,startsate,count(*) over (partition by username) as cnt,row_number() over (partition by username order by rowid asc) rn from useractivity) where rn=2 or cnt=1;

Easier Solution: with cte as (select *, row_number() over (partition by username order by CURDATE() - endDate) as recent_day_number from activity_table) select * from cte where recent_day_number in (2) or username in (select username from activity_table group by username having count(*)

with narsi as (select a.*,row_number()over(partition by username order by startdate desc) rn from activity1 a) select username,acitivity,startdate,enddate from narsi where rn=2 or username in(select username from narsi group by username having max(rn)=1);

Sir. Trigger, cursor aur user defined function ki video banayiye

One more thing I added one row for Joe having recent activity than the given one. To make the given activity second recent.

Hi, i have shared one query over mail .it is complex one can you please make a video on that one??

super! cheatwas easily installed

Awesome program

what application do you use to create the source code database?

Superb bro 👌 👏 👍

please make video on USER DEFINED FUNCTIONS in sql

group by/having/count/limit/offset - probably 3 times shorter :D

with cte as ( Select a.*, rank() over (partition by username order by startdate, enddate desc) as a_rank from activity1 a ) Select username,acitivity,startdate,enddate from cte where a_rank = 2 union all select username,acitivity,startdate,enddate from cte where username not in (Select username from cte where a_rank > 1);

Thanx

I think if one user has only 2 records. we need to consider another case also. cnt =2

select * from (select *,row_number()over(partition by username order by (select 0) ) as rownum ,count (*) over (partition by username order by (select 0) ) as count from useractivity)useractivity where rownum= case when count =1 then 1 else count-1 end

I use count and row_number logic : WITH t1 AS (SELECT *, Row_number() OVER( partition BY username ORDER BY enddate ) rn, Count(username) OVER( partition BY username) cc FROM activity1 ORDER BY username, enddate) SELECT * FROM t1 WHERE cc < 2 OR rn = 2

My solution to the problem -> 1. Get ranks based on start date partitioned by user name ordered by username and rank - store it as x, 2. select all rows from x that have have ranks < 3 and create a case when using lead() to see if the next row has the same username as current_row -> 1 if Yes, 2 if No - store it as X, 3. Select all rows from X with lead = 0

Thank you sir

Hi Taufeeq, I think if we go directly with original question then we can achieve result by using only row_number () , Right?

Sir, Will you be able to provide solution for below question? We have two records and five columns. Actually there is Duplicate record in that two records but one column is having different name for two records. So, my question is how to write a SQL query to remove that duplicate record in the Dashboard?

I think simple or clause would have done the job, like 'where rn=2 OR cnt=1'

i am not getting why count - 1 because if i want second most value it should be (adam-Dancing Not Adam-singing) cnt - 1 is correct for amy but not for adam

for sql workbench users with cte as (SELECT concat(id,' ', name) as concat,ntile(4) over(order by id) as 'ntiles' FROM interviewquestion.emp) select group_concat(concat) as result from cte group by ntiles order by 1

Hi.when it's 4 it has returned the third row but we still need only the second?

If count = 2, then cnt-1 would return the wrong value !!!, so you need to write a case for that one too. Pls reply

Hi Toufiq, How to connect with you over telegram. Thanks

Hi TFQ, i do have 6 years of experience in SQL ,which role is good ? DATA science or Analyst ,kindly make video on how to find remote jobs for SQL

Can you make video about writing sql using github copilot

Solution - select * from (select username, activity , row_number() over(partition by username order by startdate desc) rn, count(*) over(partition by username order by startdate range between unbounded preceding and current row ) as c from user_activity ) X where rn=2 or c=rn

MYSQL Solutions for Freshers With CTE as (Select *,dense_rank() over (Partition by Username order by StartDate) as Rn from Activity1), CTE1 as (Select *, Case When RN=2 then 1 Else 0 end as TRn from CTE), CTE2 as (Select *,Sum(TRN) over (Partition by Username) as TRN_Sum from CTE1) Select Username,Acitivity,Startdate,enddate from CTE2 Where (Case When TRN_SUM=1 then RN=2 Else RN=1 end);

I enrolled for the classes.. I haven’t got back anything yet

Hi TFQ May i know What is the difference b/w count (*) and count(1) and count (column)?

This seems like way too much work for a solution thah can be much simpler than this. Overcomplicating it into

Brother , sorting family members problem could u slove in MS SQL server.

create table useractivity (username varchar(50), activity varchar(50), startdate date, enddate date); insert into useractivity values ('Amy','Travel','2020-02-12','2020-02-20'); insert into useractivity values ('Amy','Dancing','2020-02-21','2020-02-23'); insert into useractivity values ('Amy','Travel','2020-02-24','2020-02-28'); insert into useractivity values ('Joe','Travel','2020-02-11','2020-02-18'); insert into useractivity values ('Adam','Travel','2020-02-12','2020-02-20'); insert into useractivity values ('Adam','Dancing','2020-02-21','2020-02-23'); insert into useractivity values ('Adam','Singing','2020-02-24','2020-02-28'); insert into useractivity values ('Adam','Travel','2020-03-01','2020-03-28'); select Row_number() over(partition by username order by startdate asc) as row,* into #temp_table from useractivity select username,count(1) as count into #final from #temp_table group by username having count(1)>1 insert into #final select username,count(1) as count from #temp_table group by username having count(1)=1 select ff.username, ff.activity, ff.startdate, ff.enddate from #final f join #temp_table ff on f.username=ff.username and ff.row=1 and f.count=1 union all select ff.username, ff.activity, ff.startdate, ff.enddate from #final f join #temp_table ff on f.username=ff.username and ff.row=2 and f.count1

Your output has not matched. Please check it once properly.

more simple solution : WITH ranked_activities AS ( SELECT *, ROW_NUMBER() OVER(PARTITION BY username ORDER BY startdate desc) AS rn, COUNT(*) OVER(PARTITION BY username) AS count FROM UserActivity ) SELECT username, activity, startdate, enddate FROM ranked_activities WHERE rn=2 OR count=1

please provide ddl scripts in video so that we can practise from ourself before watching your solution

Hi, Kindly review my code, improvement suggestions are highly solicited. Thank you. With master as ( Select *, Rank()over(partition by username order by endDate desc) as rank, Lead(endDate,1,0)over(partition by username order by endDate desc) as flag From UserActivity) Select Username, Activity, Startdate, Enddate From master Where rank =2 or flag = 0

select * from(select *, dense_rank() over(partition by username order by startDate desc) as rank, count(*) over(partition by username) as count from Google_UserActivity)x where rank=2 or count=1

with cte as ( select *,LEAD(rn,1,0) over (partition by username order by (select null) ) as ld from ( select * from ( select *, row_number() over (partition by username order by (select null) ) as rn from useractivity) A)B where rn in (1,2)) select username,activity,startdate,enddate from cte where ld=0 /*please rate this query out of 10*/

i didnt understand wat is this cte

google sql query docs public

WITH cte1 AS ( SELECT *, RANK() OVER(PARTITION BY username ORDER BY startdate DESC) AS rnk, COUNT(*) OVER(PARTITION BY username ORDER BY startdate DESC RANGE BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) AS total FROM activity) SELECT username, acitivity, startdate, enddate FROM cte1 WHERE rnk = 2 OR total = 1;

For once, the software is actually really useful

select username,ld as activity from( select *,ROW_NUMBER() over (partition by username order by startdate desc ) rnk FROM ( select *,lead(activity,1,activity) over (partition by username order by startdate desc) ld from [dbo].[UserActivity] )a) b where rnk =1

I think for adam 's second most activity is dancing right??

WITH cte AS(SELECT *, dense_rank()over (partition by username ORDER by enddate )rn, count(*) over (partition by username)cnt from useractivity) SELECT username,activity,startdate,enddate FROM cte WHERE rn = 2 or cnt =1

select username,activity,startdate,enddate from (select *,row_number() over(partition by username order by startdate desc) as rnk from useractivity) as z where rnk=2 union select * from useractivity where username in(select username from useractivity group by username having count(1)=1) solution given by SQL KING nikhil anand

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