SQL Self Join Concept | Most Asked Interview Question | Employee Salary More than Manager's Salary

In this video we will understand self join concept. Why we need it and how to do it. we will find solution for most asked interview question:
Find employees with salary more than their mangers salary

[@spd3155]

create table emp_manager(emp_id int,emp_name varchar(50),salary int(20),manager_id int(10)); insert into emp_manager values( 1 ,'Ankit', 10000 ,4 ); insert into emp_manager values( 2 ,'Mohit', 15000 ,5 ); insert into emp_manager values( 3 ,'Vikas', 10000 ,4 ); insert into emp_manager values( 4 ,'Rohit', 5000 ,2 ); insert into emp_manager values( 5 ,'Mudit', 12000 ,6 ); insert into emp_manager values( 6 ,'Agam', 12000 ,2 ); insert into emp_manager values( 7 ,'Sanjay', 9000 ,2 ); insert into emp_manager values( 8 ,'Ashish', 5000 ,2 );

[@satyanathparvatham4406]

Saviour

[@devashishduklan8154]

thnx

[@alokgupta35]

int(20) ? will it work ? i think size is not necessary

[@rishabhkesarwani5761]

@@alokgupta35 yes

[@NaveenKumar-fq4sb]

thank u

[@amrutdeshpande05]

Using Excel and pasting the manager info next to employee info was a great way of explaining! Thank you. You make the life of a Data person so easy!

[@ankitbansal6]

😊

[@dhananjaymali6242]

Correct thanks Ankit 🙌🙌... explaining same without excel was like tutor teaching to only class toppers, just imagine one who can imagine without excel can definitely solve this interview question 😅 it was just putting into syntax task for that kind of guy.

[@ajinkyaadhotre5336]

DAMN ! the two table creation on excel was soo good way of explaining ! you earned a subscriber ! 🤩

[@ankitbansal6]

Thank you 😊

[@kirankapruwan8892]

I had been searching for self join videos. But I did not understand it's working then I came across ur video and you explained in such a easy way that any layman can understand. Thank u so much. Keep doing such great work.

[@ankitbansal6]

It's my pleasure😊

[@vinipowerbi]

It became very easy to understand the concept the way you show joining manager id with the second table emp id..... Thank you so much for the clear understanding

[@ankitbansal6]

You are most welcome

[@Nikhilg-rs7iv]

Untill before watching this video I am just joining the tables withing itself and getting the empty table as result lol. Thank you Ankit bro for explaining clearly and simply.

[@user-iq8fe5nn8f]

Amazing Amazing seriously Amazing .... 👏 👏 👏 Thank you so mych

[@ayoushisingh5631]

Great way of explaination by putting the same table next to the original table. Thanks!!

[@sanam6323]

Great. Ager long years I am in the correct KZbin channel for SQL. Thanks Ankit.

[@ankitbansal6]

Keep going 💪

[@sridharmurari3007]

Great Way to explain with Excel not many would explain in Detail like this !

[@ankitbansal6]

Glad you liked it!

[@Venom-yk3wu]

the most lucid explanation on whole utube without any complication.. amazing bro !!

[@ankitbansal6]

Glad you liked it!

[@sumanacharya461]

If we just use join also it works select e.*,m.salary as sal from emp_manager as e join emp_manager as m on e.manager_id = m.emp_id where e.salary > m.salary this my query and it worked

[@sanjanashuklaa2031]

video was crystal clear😍😍 i don't know how effortlessly i understood this concept because it was you who was explaining thankyou plz make more video on other concepts

[@ankitbansal6]

Glad to know 🙂

[@vinitpatidar5617]

Most simple explanation. Thanks

[@naveennvnkumar4615]

You make SQL look so easy, really good. Thanks mate

[@ankitbansal6]

🙏

[@debasmitabanerjee2835]

Best explanation!!!!

[@shuaibsaqib5085]

Hi Ankit, Kindly post the Table schema queries in the description for reference and solution query too..

[@dfkgjdflkg]

as usual, great content. You have been a guru to us. Thanks for your time. It is a selfless act. Thanks again

[@ankitbansal6]

My pleasure!

[@sairajesh6895]

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

[@anchitgupta4772]

I have solved this question same way in leetcode

[@rahulranjan6740]

very crystal clear and detailed explanation

[@ankitbansal6]

Glad you liked it😊

[@pspreetesh4166]

sir why did you give inner join instead of self join? inner join only gives common records b/w 2 tables and self join used for 1 table by itself. Please answer

[@surajkurle6962]

thank u very easy

[@dudechany]

Well Ankit's salary is greater than his manager's salary at Amazon 😀. Nice tutorial btw. Great work.

[@ankitbansal6]

Haha 😃

[@aniketraut6864]

Thank you for these amazing videos its helping me to learn the sql in simplest way.

[@ankitbansal6]

Great to hear!

[@shubhamsri4561]

Your video is very helpful, sir. The way you explain complex concepts is very understandable

[@ankitbansal6]

Great 😊

[@prithak3263]

great way of explaining. kudos!

[@enjoyfriends873]

Hi Ankit Thank you 🙂 If possible please share the create table and insert statements for every video Oracle create table emp_manager( emp_id number, emp_name varchar2(50), salary number, manager_id number ); insert into emp_manager values( 1 ,'Ankit', 10000 ,4 ); insert into emp_manager values( 2 ,'Mohit', 15000 ,5 ); insert into emp_manager values( 3 ,'Vikas', 10000 ,4 ); insert into emp_manager values( 4 ,'Rohit', 5000 ,2 ); insert into emp_manager values( 5 ,'Mudit', 12000 ,6 ); insert into emp_manager values( 6 ,'Agam', 12000 ,2 ); insert into emp_manager values( 7 ,'Sanjay', 9000 ,2 ); insert into emp_manager values( 8 ,'Ashish', 5000 ,2 );

[@bhaveshbharti4782]

Thanks for so clear explanation. Understood

[@ankitbansal6]

Great to hear!

[@raushansingh7530]

select emp.emp_name as Employee_name from emp_manager as emp inner join emp_manager as manager on emp.manager_id = manager.emp_id where emp.salary > manager.salary Thanks Ankit sr

[@RohithS-ig4hl]

Thanks for this Ankit. It was really helpful for me in understanding the concept of self joins. Really appreciated!

[@ankitbansal6]

Glad to hear that

[@praveenkumarrai101]

create table emp_manager(emp_id int,emp_name varchar(50),salary int,manager_id int); insert into emp_manager values( 1 ,'Ankit', 10000 ,4 ); insert into emp_manager values( 2 ,'Mohit', 15000 ,5 ); insert into emp_manager values( 3 ,'Vikas', 10000 ,4 ); insert into emp_manager values( 4 ,'Rohit', 5000 ,2 ); insert into emp_manager values( 5 ,'Mudit', 12000 ,6 ); insert into emp_manager values( 6 ,'Agam', 12000 ,2 ); insert into emp_manager values( 7 ,'Sanjay', 9000 ,2 ); insert into emp_manager values( 8 ,'Ashish', 5000 ,2 );

[@milindzuge906]

Thanks Ankit, Great Content❣

[@vishnujatav6329]

Very nice explanation

[@ankitbansal6]

Thank you

[@Travelling_With_Kamalu]

Thank you sir. For the explanation.very clear

[@ankitbansal6]

You are welcome

[@lazygeek431]

great, thanks for the explanation

[@ankitbansal6]

You are welcome!

[@LS8636]

Thanks for making it so easy

[@adityakaushik6417]

Thanks for this example ! what would be the solution to find out those employees who have highest salary under each manager.

[@ankitbansal6]

Rank partition by manager and filter

[@aashishmalhotra]

Awesome Ankit got your channel from Linkeidin and its best thing happened.

[@hiteshjanuskar7319]

Very helpful concept 👍🏻

[@ankitbansal6]

Glad it was helpful!

[@techgalaxy100]

Very well explained brother.

[@ankitbansal6]

Glad it was helpful!

[@gauravthukral7042]

Great explanation 👍

[@ankitbansal6]

Thank you 😊

[@pavangsk8404]

lovely explaining

[@ankitbansal6]

Thank you! 🙂

[@ashish-blessings]

Thank you so much

[@mohiuddinansari9356]

Well explained, thank you so much. Subscribed !

[@ankitbansal6]

Awesome, thank you!

[@nishantbodke]

thank you so much dude you're a god

[@vsagar4b38]

Very nicely explained

[@ankitbansal6]

Keep watching🙌

[@mahesh6701]

SELF JOIN concept explained in the best way. thanks a lot. Could you please explain INDEX and CLUSTER INDEX and NON-CLUSTER INDEX concepts please?

[@ankitbansal6]

Noted

[@mohitmalviya1928]

grt work sir

[@ankitbansal6]

Thanks a lot

[@user-bd8li1xz1x]

Can we combine different columns using inner join

[@sauravips]

Beautifully explained

[@ankitbansal6]

Thank you so much 🙂

[@muazmalik601]

one more solution: with cte as(select A.* , B.Salary as manger_salary from emp_manager as A, emp_manager B where A.manager_id=B.emp_id) select emp_id, emp_name from cte where salary> manger_salary

[@explorer_baba2750]

please explain the reason for the join connection based on a.manager_id = b.id? why we cant use a.id = b.manager_id?

[@ankitbansal6]

You can do that also. Accordingly you will have to use alias for manager name and emp name and salary.

[@explorer_baba2750]

@@ankitbansal6 thanks

[@Vedantsinghvi1611]

Hello Why is manager id taken from the employee table And not manager table? Thanks

[@meerasrinivasagopalan9662]

Clear explanation! thank u!

[@ankitbansal6]

Glad you liked it 😊

[@sayansengupta8207]

Superb!!!!

[@ganeshtaware9883]

Thanks

[@spacespectale]

please upload data set as well or provide drive link whenever u upload practical

[@arpitmishra1783]

nicely explained!

[@ankitbansal6]

Glad you liked it

[@vutv5742]

Completed ❤

[@vishalsonawane.8905]

Done

[@PriyankaPatil-nj2qb]

Thank you sir..

[@ankitbansal6]

Most welcome

[@sass520]

Hello Sir, You mentioned self join but in the answer you used Inner Join

[@rajeshgoud9619]

hello ankit what if one of the manager id is null and how it will join in that case to get emp salary>mgr salary

[@ankitbansal6]

If an employee does not have a manager then you cannot compare.

[@divyagouda5285]

Hi.. i have employee table in that we have ename and sal columns. From employee table we need employee name who is getting max sal without using analytical,order by and aggregate functions. How can we do any one help on this

[@rajivjain6165]

Hi Ankit Could you make video on performance tunning topic.

[@ankitbansal6]

Sure

[@pavan5208]

Hi Ankit, thanks for the clear explanation. Small question on the JOIN part. Any particular reason for using INNER JOIN there? LEFT JOIN would also work and produce similar result there right?

[@ankitbansal6]

Yes but there is no need of left join.When inner join works then why to use left join.

[@radhikajujjavarapu6971]

INNER JOIN is optimized than OUTER JOIN

[@uttamthakur2016]

@@ankitbansal6 I realized one thing how Emp_id = 1 is getting in output even though 1 is not present in manager_Id ? I am trying to match output but not matching .

[@neelshah8803]

Hi Ankit, Can you please make videos on Python and ML please would be really helpful. Thanks

[@satyamtyagi3076]

Hi Ankit, Correct me if I'm wrong, Don't you think that 'emp_id: 1, emp_name: Ankit' should not come in the result as you have used inner join on the emp_id = manager_id.

[@ankitbansal6]

But Ankit's manager id is present in table in emp I'd column.

[@niveditasingh1176]

Hey Ankit, if we write query as " on e.emp_id = m.mgr_id" and rest query remains same will it yield same result?

[@ankitbansal6]

Nope

[@Ramesh00300]

@@ankitbansal6 can you please explain why the queries are giving different results when we are changing the on condition?

[@ankitbansal6]

@@Ramesh00300 you need to watch the video again to understand

[@mohitmotwani9256]

When specifying a condition in the WHERE clause, it applies after the join has been performed. This means that the join conditions defined in the ON clause have already been applied, and the WHERE clause further filters the resulting data. In contrast, the ON clause specifies the conditions for joining tables. It dictates how the tables are connected, such as matching columns or other relationships. This condition is used during the join itself, influencing which rows from both tables are combined.

[@AnilKumar-oe1bb]

Can you please give more real time scenarios where Self Join is used?

[@sanilkumarbarik9151]

Since it's 4 days and nobody replied to your comment, I would recommend you to ask the same question to ChatGPT.

[@hellotohappiness1028]

please increase ur voice ..just now i subscribed

[@ankitbansal6]

Sure

[@umeshroy6898]

when I run the query say table does not exit

[@arbazadam3407]

Hi, i have a slightly different question to ask. How can i put a check constraint on the manager_id column such that it shouldn't have any other values except for the ones present in emp_id in postgresql

[@ankitbansal6]

We can put a forein key constraint

[@arbazadam3407]

@@ankitbansal6 thanks dude. I wasn't aware that we can add a foreign key constraint to the same table.

[@ankitbansal6]

@@arbazadam3407 we can 😊

[@amritasinha2784]

If any employee is not having any manager , I mean NULL. Then how to write that? I want NULL in the columns manager_name and manager_salary.

[@ankitbansal6]

Just do left join

[@yatinshekhar787]

3/122

[@siramar2453]

can I write :- Table name - emp_manager select e.empid, e.salary, m.manager_id, m.salary from emp_manager as e, emp_manager as m where e.salary > m.salary; pls sir tell me .

[@techtalk9903]

god bless u xdd

[@moyeenshaikh9915]

Sir, if we inner join emp id of emp with manager id of manager table, will it work same?

[@ankitbansal6]

No.

[@moyeenshaikh9915]

@@ankitbansal6 how to imagine sir which column to take on left table and which one on right

[@ankitbansal6]

@@moyeenshaikh9915 watch video again

[@TechnoSparkBigData]

could you please share script to create these tables?

[@mohammadabdullahansari6314]

create table emp_manager ( emp_id int, emp_name varchar(20), salary int, manager_id int); insert into emp_manager values (1,'Ankit',10000,4),(2,'Mohit',15000,5),(3,'Vikas',10000,4),(4,'Rohit',5000,2), (5,'Mudit',12000,6),(6,'Agam',12000,2),(7,'Sanjay',9000,2),(8,'Ashish',5000,2); select * from emp_manager;

[@vanshgrover_19]

Why did he use INNER JOIN and not SELF JOIN? Please someone tell me!

[@ankitbansal6]

There is no keyword as self join. When you join a table with itself it's called self join.

[@vanshgrover_19]

@@ankitbansal6 can't we do this question by joining this employee table with itself?

[@ankitbansal6]

​@@vanshgrover_19 that's what we have done

[@amritasinha2784]

Tables: Employee: Employee_Id name salary 1 Ram 4500 2 Gopi 17500 3 shyam 9500 4 Nisha 13500 Salary_range: From_sal To_sal Grade 0 5000 A 5001 10000 B 10001 15000 C 15001 20000 D Output: Name Grade Ram A Gopi D shyam B Nisha C I need a query to get the output result.

[@ankitbansal6]

Just join with condition salary between from sal and to salary

[@theraizadatalks14]

Below Query will give the desired result: Select E.emp_name as 'Name',S.Grade from EmployeeT E Inner join Salary_range S on E.salary between S.From_Sal and S.To_Sal Here is the table scripts for the same: create table EmployeeT( emp_id int, emp_name varchar(20), salary int,) insert into EmployeeT values (1, 'Ram', 4500); insert into EmployeeT values (3, 'Gopi', 17500); insert into EmployeeT values (3, 'Shyam', 9500); insert into EmployeeT values (4, 'Nisha', 13500); create table Salary_range( From_sal int, To_sal int, Grade varchar(20), ) insert into Salary_range values (0,5000,'A'); insert into Salary_range values (5001,10000,'B'); insert into Salary_range values (10001,15000,'C'); insert into Salary_range values (15001,20000,'D');

[@akashwatar6633]

1

[@mohammadabdullahansari6314]

Please share the script to make the table.

[@mohammadabdullahansari6314]

Nvm, I created the script: create table emp_manager ( emp_id int, emp_name varchar(20), salary int, manager_id int); insert into emp_manager values (1,'Ankit',10000,4),(2,'Mohit',15000,5),(3,'Vikas',10000,4),(4,'Rohit',5000,2), (5,'Mudit',12000,6),(6,'Agam',12000,2),(7,'Sanjay',9000,2),(8,'Ashish',5000,2); select * from emp_manager;

[@vignesh9173]

I solved a similar problem on Leetcode today! Used sub queries for it!

[@ankitbansal6]

Cool

[@vignesh9173]

This was a really good explanation! I’ll definitely be following your videos! :D

[@dikshachourasiya5561]

can't we use this condition on e.emp_id=m.manager_id ? Using this giving different output

[@rajunaik8803]

scripts: create table emp_manager(emp_id int,emp_name varchar(20),salary int,manager_id int); insert into emp_manager values(1,'Ankit',10000,4); insert into emp_manager values(2,'Mohit',15000,5); insert into emp_manager values(3,'Vikas',10000,4); insert into emp_manager values(4,'Rohit',5000,2); insert into emp_manager values(5,'Mudit',12000,6); insert into emp_manager values(6,'Agam',12000,2); insert into emp_manager values(7,'Sanjay',9000,2); insert into emp_manager values(8,'Ashish',5000,2); select * from emp_manager; with cte1 as( select e.emp_id,e.emp_name,m.emp_name as manager_name,e.salary as emp_salary,m.salary as manager_salary from emp_manager e join emp_manager m on e.manager_id=m.emp_id ) select * from cte1 where emp_salary>manager_salary

[@the_class_apart]

To find employees whose salary is more than manager we could have filtered during JOIN only while declaring ON condition as: FROM emp e JOIN emp m ON e.manager_id = m.emp_id AND e.salary>m.salary;

[@ankitbansal6]

In case of inner join both are same 😊

[@rishabhkesarwani5761]

Solution Alert select emp_id,emp_name,emp_salary,manager_id, manager_salary from( select a.emp_id,a.emp_name , a.salary as emp_salary,a.manager_id ,b.salary as manager_salary from emp_manager a join emp_manager b on a.manager_id =b.emp_id ) where emp_salary > manager_salary

[@angelnadar1209]

Thanks Ankit ! I understood this but under self join , I came across a different question from sqlzoo: stops:stops(id, name) route(num, company, pos, stop) Find the routes involving two buses that can go from Craiglockhart to Lochend. Show the bus no. and company for the first bus, the name of the stop for the transfer, and the bus no. and company for the second bus. I tried to find the solution but getting some error: Could you please take this type of example . I also saw some solutions but coudn't understand it .like below is an working soution for above question but I didn't understood on what basis they are joining on company and num fields ? Sol: SELECT a.num, a.company, stops.name, d.num, d.company FROM route a JOIN route b ON a.company = b.company AND a.num = b.num JOIN stops ON b.stop = stops.id JOIN route c ON c.stop = stops.id JOIN route d ON c.company = d.company AND c.num = d.num WHERE a.stop = (SELECT id FROM stops WHERE name = 'Craiglockhart') AND d.stop = (SELECT id FROM stops WHERE name = 'Lochend') ORDER BY a.num, stops.name, d.num It woud be helpful if you can help me to understand on what basis they are joining on company and num fields ?

[@ankitbansal6]

Sure I will check that question.

[@raushansingh7530]

SELECT emp_name FROM emp_manager e WHERE salary > ( SELECT salary FROM emp_manager WHERE emp_id = e.manager_id ); this is another approach

[@manjumohan7731]

@ankitbansal6 :I thought self join will have where clause and condition and no need of join cause. Can you plz clarify whether self join and inner join are one and the same as the syntax of both is different and whether can it be used interchangeably Using self join for Emp Salary >Manager Salary: select e1.emp_id as Emp_id, e1.emp_name as employee_name, e1.salary as emp_salary, m1.emp_id as Manager_id, m1.emp_name as manager_name, m1.salary as manager_salary from emp3 e1,emp3 m1 where m1.emp_id=e1.manager_id and e1.salary>m1.salary order by emp_id;

[@ankitbansal6]

It's same thing