SQL Interview Problem asked by Product Based Company | Solving SQL Interview Query 

Thanks for your video. I try to solve this problem first and here are my code. select id_name + ', ' + name2 as result from (select *, lead(id_name) over (order by id) as name2 from (select *, cast(id as varchar) + ' ' + name as id_name from emp_input) x) y where id % 2 0

Table name is input SELECT concat(a.id,' ',a.name,' ',b.id,' ',b.name) from input as a JOIN input as b On a.id < b.id WHERE a.id%2 = 1 and b.id%2 = 0 and b.id- a.id = 1

I learn and learned all tricky SQL part from your videos only..request you to make video on "sql Index" with practical examples

Loved your solution! It is a superior solution for the problem. I tried solving it before watching your solution and came up with this. If record is odd, combine text from this row and leading row. So much to improve! thanks for everything! select * from (select case when id%20 then id||' '||name||', '|| lead(id) over (order by id) || ' '|| lead(name) over (order by id) end as res from input) x where x.res IS NOT null;

Very Well Explained. MySql Solution: SELECT GROUP_CONCAT( CONCAT_WS(', ', CONCAT(id,' ',name))) as Result FROM ( SELECT id, name, ntile(20) over(order by name) as grp FROM `workers` ) as temp GROUP BY grp;

Applicable, concise, and practical. Thank you 👏🏽

with odd as ( select * from emp_input where id%20 ), even as ( select * from emp_input where id%2=0 ) select concat(odd.id," ",odd.name,",", even.id," ",even.name)as output from odd,even where even.id = odd.id+1 this is my solution

Logic is this with cte1 as (select * from emp_input where id%2=0), cte2 as (select * from emp_input where id%20) select * from cte1 a inner join cte2 b on a.id=b.id+1

Great explanation, got to learn about the ntile function today, thanks a lot sir!

I haven‘t really verified my thoughts but I‘d rather go with the mod function to create buckets. In this case you won’t have to speficy how many buckets you need (you just need to think of the size of each bucket and use the row number as numerator). For this exact problem though, is your way of solving it, just perfect! Thanks for sharing 👍

My Simple Solution with Logic :- Simply assign group number to all the records such that Emp1 and Emp2 go to group 1, Emp3 and Emp4 go to group 2 and so on. This can be simply done by dividing their serial number by 2 and then doing a ceil on it to ensure it is an integer. Now you can apply group concat based on this column. create table data( ID int, Name varchar(20) ); insert into data values (1,'Emp1'), (2,'Emp2'), (3,'Emp3'), (4,'Emp4'), (5,'Emp5'), (6,'Emp6'), (7,'Emp7'), (8,'Emp8'); select grp_no,group_concat(res_col) from( select concat(ID,' ',Name) as res_col,ceil(ID/2) as grp_no from data ) A group by grp_no;

I have learned a lot from your videos! A lot of things that I thought were complex and that were actually simple to understand. Thank you so much for everything and congratulations for the channel!!

sir, make more videos on solving interview question , best teaching method and the way you explain each and every line is very much understandable. Thank you sir.

I have tried this..! Select Convert(varchar,X.ID)+' '+X.name+', '+ Convert(varchar,X.a) +' '+ b From ( Select ID, name, Lead(ID,1) Over(order by ID asc) a, Lead(Name,1) Over(order by Name asc) b From Input )X Where X.ID%20 Order by 1 asc

I solved it using self join with cte as( select e1.id id1,e2.id id2 ,e1.name name1 ,e2.name name2 from emp_input e1 left join emp_input e2 on e1.id+1 = e2.id where e2.name is not null and e1.id % 2 0 ) select concat(id1,name1,',',id2,name2) output from cte

your videos are the most helpful ones

select concat(a.id,' ',a.name,', ',b.id,' ',b.name) from (select * from emp_input where id%20) a join (select * from emp_input where id%2=0) b on a.id=b.id-1

Simply one of the best channels!!!

WITH CTE_1 (col_id,Name, LeadID, LeadName) as ( select col_id, Name, lead(col_id) over (order by col_id) LeadID , lead(Name) over (order by col_id) LeadName from demo2 order by col_ID ), CTE_2 (CIS) as -- since CASE CIS can not be used in where clause ( select (case when MOD(col_id,2) =1 then col_id || Name || ' , ' || LeadID || LeadName Else NULL END) as CIS from CTE_1 ) -- WHERE is processed before SELECT. It doesn't know what DerviedRegion is at that point. select * from CTE_2 where CIS IS NOT NULL

I saw one video of yours and I completely understood Sir I want to learn SQL in a proper manner can please suggest me your playlist which one I need to refer . Hope you will reply 😊

Your Videos are very helpful, gained more knowledge through your videos and I like the way you are explaining step by step and providing every dataset for practise ,Thanks a lot

Please upload every week solve SQL projects, also could you please start a tutorial series for SQL 0 to 360 Degree❤

My approach using CTE, concat, MOD and join :- create table data (id int, name text); insert into data values (1,'Emp1'); insert into data values (2,'Emp2'); insert into data values (3,'Emp3'); insert into data values (4,'Emp4'); insert into data values (5,'Emp5'); insert into data values (6,'Emp6'); insert into data values (7,'Emp7'); insert into data values (8,'Emp8'); solution :- with set1 as (select *,row_number() over() as rec, concat(id,' ',name) as id_name from data where id%2 0), set2 as (select *,row_number() over() as rec, concat(id,' ',name) as id_name from data where id%2 = 0) select concat(s1.id_name,', ',s2.id_name) as Result from set1 s1 join set2 s2 on s1.rec=s2.rec; Thanks @techTFQ for such efforts 👍👍

we can try like this also with cte as ( select *, concat(id,+' '+ name ) as nm from emp_input) ,final as ( select *, lead (nm,1)over (order by id) as new from cte ) select concat(nm,+','+new), id from final WHERE id%2 0;

easy method use case statement for oracle select*from(select case when id=1 then '1 emp1,2 emp2' when id=2 then '3 emp3,4 emp4' when id=3 then '5 emp5,6 emp6' when id=4 then '7 emp7,8 emp8' end finalre from emp_input) where finalre is not null;

Hi Thoufiq, I came up with this solution without using any window functions or cte SELECT x.empo||', '||y.empe AS RESULT FROM (SELECT id, id||' '||name empo FROM input i1 WHERE MOD(id, 2) != 0) x , (SELECT id, id||' '||name empe FROM input i2 WHERE MOD(id, 2) = 0) y WHERE y.id - x.id = 1

You didn't use the within group order by clause in the string aggregate function. It's possible to get 2 Emp2, 1 Emp1, etc. I know because that is what I got when I left out the order clause select string_agg (concat (ID,' ', Name) , ', ' ) within group (order by ID) as output from emp_input group by round(ID/2.0, 0) /* create buckets */ What about creating one long string and then cutting it into distinct pieces...is that possible with no grouping or window clause?

Extremely good instruction, bro

Liked your solution only ;-)

The query below works in MySQL. with a1 as ( select CONCAT(ID,'',NAME,', ') as nlist, row_number() over (order by ID) as RN from emp_input where id%2=1 ), a2 as ( select CONCAT(ID,'',NAME) as nlist, row_number() over (order by ID) as RN from emp_input where id%2=0 ) select concat(a1.nlist,a2.nlist) from a1 join a2 on a1.RN=a2.RN order by a1.RN; This also works in MySQL based on one comment under this video: SELECT CONCAT(A.id, ' ', A.name, ', ',B.id, ' ', B.name) FROM emp_input AS A INNER JOIN emp_input AS B ON A.id + 1 = B.id and A.id % 2 0;

with cte as (select *, ntile(4) over() result1 from input) select group_concat(id," ",name) Result from cte group by result1

As an absolute beginner who started learning simple select statements, my solution was: select concat(id,name, ',' , id+1,' Emp',id+1) as Output from tbl where mod(id,2) 0; of course, this fails miserably if all names are not simply Emp and number. So, if we want to stick to very basic syntax, is it possible to concat outputs from two select statements (one with mod(id,2) 0 and the other mod(id,2) =0 in anyway? I love this site and I am sure I will be spending a lot of time here.

I started watching your videos , very excellent explanation . will wait for more such videos.

with cte as (select concat(id,' ',name) as result from input) , cte2 as (select result, lead(result,1) over(order by result) end from cte) select concat(result,', ',end) as result from cte2 where result%2 != 0

Awsome that was easyily done...thanks brother...

select string_agg(Concat(id, ' ', name), ', ') from emp_input group by id - case when id % 2 = 0 then 1 else 0 end;

This is easiest solution you will ever find for this question: select concat(row1,' ',name1,',',row2,' ',name2) as result from (select e1.id as row1,e1.name as name1,e2.id as row2,e2.name as name2 from emp_input e1 join emp_input e2 on e1.id+1=e2.id where row2%2==0)

My Approach before watching the solution: with cte as (select *, concat(id ,name) as hello from productBased), cte1 as (select id,name, lag(hello) over(order by name) as hello2 ,hello from cte) select concat(hello2,",",hello) from cte1 where id%2=0;

Nice Solution Brother Can't we do it using case statements and then using concat and max ? Please Suggest

My solution (applicable only when total number of records in input table is even) with cte as (select id, concat(id, name, ', ', lead(concat(id, name)) over (order by id)) as output from input) select output from cte where cte.id%2 = 1;

thanks a lot sir. it would be great if you post list of interview based sal questions and solutions as you did before. it really helped me

Excellent explanation bro.... 👍👍👍 Loved it

Thanks for these kind of videos

You are amazing bhai, thank you

My solution SELECT id || ' ' || name || ',' || id_lead || ' ' || name_lead from ( SELECT id, lead (id,1,id) over (order by id) as id_lead, name, lead (name,1,name) over (order by id) as name_lead, mod(id,2) as flag from tablename ) as X where X.flag 0 ;

That’s grt bro , 🎉

Nice explanation bro 👍 👌 👏

with a as (select x.id as id1,x.name as name1,y.id as id2,y.name as name2, ROW_NUMBER() over (partition by x.id order by x.id) as rn from p3_tab as x inner join p3_tab as y on (x.id%2)!=0 and x.id

Thanks a lot, Great detailed video. Please make video detail video on Match_recognize() function.

You are awesome!

It will work with any dataset as long as the total count is in even. .. .. WITH cte1 AS ( SELECT (COUNT(*)/2)::INT AS total FROM input), cte2 AS ( SELECT (id || ' ' || name) AS result, NTILE(total) OVER(ORDER BY id ASC) AS pairs FROM input, cte1) SELECT STRING_AGG(result, ', ') AS RESULT FROM cte2 GROUP BY pairs ORDER BY 1 ASC;

Awesome explanation ❤️

for oracle sql select listagg(full_name,',') from (select employee_id||first_name as full_name, ntile(4) over(order by employee_id) as bucket from emps) group by bucket;

Thank you so much Bro!!

Good evening. I am teaching myself MySQL on Workbench to apply for Data Analyst profile later on. Do you have any compilation of relevant SQL problems that I can use to practice along? Thanks.

AWSOMEEEEEEEEE

HI Taufiq , Sharing my solution %sql WITH CTE AS (select *,concat(id,' ',name) as new_val from emp_input) ,CTE1 AS (select *,concat(new_val,',',lead(new_val,1,'NothingtoADD') over(order by id)) as new_val2 from CTE) select * from CTE1 where id%2!=0

select concat(B.Id -1,B.Name,",",A.Id, A.Name) from (select * FROM Employee where Mod(Id,2)=0 ) A inner join (select Id+1 as Id,Name FROM Employee where Mod(Id,2)!=0 ) B on A.Id = B.Id

select case when id%2 =1 then out else null end as result from ( select *,CONCAT(id,' ',name) +','+ lead (CONCAT(id,' ',name),1) over (order by id) as out from emp_input) a where case when id%2 =1 then out else null end is not null;

Awesome

All I did differently was use ceil(id/2) as buckets

Here my solution :)) select concat(x.id, x.name, ',', x.lead_id, x.lead_name) as result from ( select * , lead(id,1) over() as lead_id , lead(name,1) over() as lead_name from emp_input e1 ) x where mod(x.id, 2) 0;

Thanks

Hi Toufiq, what is the difference between order by(column_name) and order by 1. along with the difference between count(column_name), count(*) and count 1. kindly do one separate video. Thanks

Sir I have learned Oracle SQL, so my question is that learning PL/SQL will give me a added advantage or it's not that necessary

This can be done without using CTE: select string_agg(name, ',') as Result from (select concat(id, ' ' , name) as name, ntile(4) over() as bucket from emp_input) as innerTable group by bucket order by bucket

👌🏻👌🏻👌🏻👌🏻👌🏻👌🏻

Sir, Trigger, cursor aur user defined function par video banayiye

please make video on USER DEFINED FUNCTIONS in sql

Thanks bro

Please make videos on hive queries bigdata

Explaing phase is very fast, some may not catch up your speed, otherwise your explanation is very good.

string_ agg it can be used in oracle

Can you make videos on product metrics

Mine is shorter and more readable: --select t1.id, t1.name, t2.id, t2.name select t1.id || " " || t1.name || ", " || t2.id || " " || t2.name -- sqlite3-syntax from emp_input t1 join emp_input t2 on t1.id+1=t2.id where (t1.id-1)%2=0 But both are rubbish for the general case.

Done

MySQL Solution (For Freshers) With CTE as (Select *,concat(id," ",Name) as N1 from emp_input), CTE2 as (Select *,Lead(N1,1) Over (Order by id) as N2,row_number() over (Order By id) as RN from CTE) Select concat(N1,",",N2) as Result from CTE2 Where N2 is not null and Rn%2!=0;

with temp as ( select id,case when mod(id,2)=1 then id+1 else id end new_id, id||' '||name as new_name from emp) select listagg(new_name,',') from temp group by new_id

Make a video on views

Hey there, God bless your efforts. I am still new to sql with a general enquiry. How non-clustered index differs from clustered index? It has anything to do with grouping of data while indexing? Thanks a lot.

WITH t1 as(select *, id||' '||employee as joined FROM sample), t2 as (SELECT id, joined, LEAD(joined,1) over () as result from t1) select joined||', '||result from t2 WHERE (id*1.0)%2 != 0

what if you do not know the number of rows are 8, how would you generalize for any number of rows?

select full_data from (select concat_ws(" ",id,name, lead(id,1,'empty') over(), lead(name,1,'no_name') over()) as full_data,lead(id,1,'empty') over() as num from emp_input) new_table where mod(num,2) = 0 and num not like 'empty';

My Code for that problem with combines as ( select id, name, concat(id,' ',name) as concats from emp_input ) , rnking as ( SELECT id, name, concats, row_number()over(order by concats) as rnks from combines ), new_rnking as ( SELECT id, name, concats, rnks, case when rnks%2=0 then rnks - 1 else rnks end as new_rnks from rnking ) SELECT GROUP_concat(concats separator ',') as Result from new_rnking GROUP by new_rnks

Input id product 1 Choc 2 cadb 3 dairy 4 Choc 5 ecli 6 Choc 7 milky Output id product Sta 1 Choc 1 2 cadb 2 3 dairy 3 4 Choc 1 5 ecli 2 6 Choc 1 7 milky 2 when product choc encountered irteration should reset , can you help to provide a saolution

String _agg function is not working in Oracle, it is showing invalid identifier. Why???

WITH cte1 AS (SELECT *, CONCAT(id,name) as mer_name, CASE WHEN id%2=0 THEN id ELSE LEAD(id) OVER(ORDER BY id) END ids FROM emp_input) SELECT GROUP_CONCAT(mer_name) as results FROM cte1 GROUP BY ids;

We Hire dedicated teacher. Here is a jsp page and on the other hand asp page now here is a store procedure that need to be invoked. What purpose it will solve this is none of your business. Time will explain you.

Hi, when is your next class?

Pls show answers in my sql too

Hi Toufiq, Please check this solution : SELECT CONCAT(A.id, ' ', A.name, ', ', B.id, ' ', B.name) AS Req_Result FROM emp_input AS A INNER JOIN emp_input AS B ON A.id + 1 = B.id WHERE (A.id % 2 0) ;

Hi help me on this how to create unique id but I'd contains date-number, numbers is reset when the date is changed. Number start from 1

Bro from last two days I am trying to make payment for the course... tried with four different cards ...lighthall site simply says card is declined...Is there any other way to make payment?

I think we can do this by concat and self join also

my approach select (emp_in||','||leadd )as Result from ( select emp_in,lead(emp_in) over()as leadd,row_number() over() as row_no from (select (id||' '||name)as emp_in from emp_input)as a ) as aa where mod(row_no,2)!=0

Can you please share notes for SSRS and SSIS

HI, here is my version of solution for MYSQL with cte1 as (SELECT concat(id," ",name) as result from emp_input), CTE2 as (SELECT result, LEAD (result) over() as result2 FROM cte1) SELECT concat(result, "," " ",result2) as final_result FROM cte2 where mod(concat(result, "," " ",result2),2)=1

SELECT id || name || ‘,’ , LEAD(id) OVER(), LEAD(name) OVER() FROM table_name WHERE MOD(id,2) 1

Here is my Solution - select * from ( select case when id%2!=0 then concat(id,' ',name,', ',lead(id) over(order by id),' ',lead(name) over(order by id)) end as RESULT from emp_input ) a where a.result is not null;

The solution you've provided is not viable when the number of rows change. Here is my solution which is not dependent on number of rows. with cte as (select *,case when id % 2 = 0 then 0 else 1 end as num from emp_input), t as( select *, rank() over(partition by num order by id) as rk from cte) select concat(t2.id,' ',t2.name,',',t1.id,' ',t1.name) as result from t t1 join t t2 on t1.rk =t2.rk and t1.id t2.id group by t1.rk