Most Asked SQL interview questions and answers for Java Developers with examples | Code Decode

In this video of code decode we have covered most asked SQL Interview Questions and answers for java developer with examples for both freshers and experienced.
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SQL interview question and answer part 2 : • SQL Interview Question...
Databases can be found in almost all software applications. SQL is the standard language to query a database. Thus most asked sql interview questions is a must go through before any java interview questions faced in real time
We live in a data-driven world: people search through data to find insights to inform strategy, marketing, operations, and a plethora of other categories. There are a ton of businesses that use large, relational databases, which makes a basic understanding of SQL a great employable skill not only for data scientists, but for almost everyone.
Structured Query Language or SQL is a standard Database language which is used to create, maintain and retrieve the data from relational databases like MySQL, Oracle, SQL Server, PostGres, etc
As the name suggests, it is used when we have structured data (in the form of tables). All databases that are not relational (or do not use fixed structure tables to store data) and therefore do not use SQL, are called NoSQL databases. Examples of NoSQL are MongoDB, DynamoDB, Cassandra, etc
How to find third height Salary is very frequently and most asked sql interview questions
What are Indexes and How to create an index in SQL? you will always face this as most asked sql interview questions
Indexes are database objects which help in retrieving records quickly and more efficiently. Column indexes can be created on both Tables and Views. By declaring a Column as an index within a table/ view, the user can access those records quickly by executing the index. Indexes with more than one column are called Clustered indexes.
Syntax:CREATE INDEX INDEX_NAME ON TABLE_NAME(COL1, COL2);
The syntax to drop an Index is DROP INDEX INDEX_NAME on TABLE_NAME;
Indexes are known to improve the efficiency of SQL Select queries
Suppose we need to search by employee name = Manoj
What goes on behind the scenes is Every single row is checked to see if the employee_name matches with Manoj. This effectively means that the entire table will have to be scanned (known as the full table scan).
An index is a data structure that stores the values for a certain specific column of a table and helps us avoid a full table scan.
Database Indexing in reality, allows us to cut down the number of rows/records that need to be examined when a select query with a where clause is executed.
Few DS are :
B-tree - Database indexes will also store pointers which are simply reference information for the location of the additional information in memory. Basically the index holds the company_id and that particular row’s home address on the memory disk.
The query looks for the specific row in the index; the index refers to the pointer which will find the rest of the information.
Index takes up additional space, so the larger the table, the bigger the index.
Every time you perform an add, delete, or update operation, the same operation will need to be performed on the index as well.
If we drop a table, does it also drop related objects like constraints, indexes, columns, default, views and stored procedures?
Yes, SQL server drops all related objects, which exists inside a table like constraints, indexex, columns, defaults etc.
But dropping a table will not drop views and sorted procedures as they exist outside the table.
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[@vinaykumarjashtadhi3107]

Hi, I was not able to find the best query for finding the nth highest salary of an employee, but with this video I found it very simple to remember, thanks for this video. Also, please proceed further with other SQL questions you mentioned at the last.

[@CodeDecode]

Thanks . Sure Vinay 🙂👍

[@vengateshm2122]

Pls check out row number concept. We can also do with that approach.

[@sarthakpalsharma4501]

Please upload further videos. It will increase the employment rate of India because your videos are gem.

[@CodeDecode]

Thanks a ton Sarthak 🤣🤣. Sure we will upload more videos 👍👍.

[@manojpatil2457]

@@CodeDecode that cracked me up too 😂😂

[@priteshbohrade8548]

A gem comment..

[@ahmetyasarozer]

Hello. Thanks a lot for the videos. Cheers. Note: I guess there is a gaffe at 7:15: Indexes with more that one column are called "composite indexes", not "clustered indexes".

[@LT-js2yk]

Great video! one correction though.. Clustered indexes are indexes whose order of the rows in the data pages corresponds to the order of the rows in the index.

[@shubhamraj2683]

The way you teach is superb.. the concepts i wasn't able to grab after learning for days, you explain it so effectively that I understand it in a single watch.

[@CodeDecode]

Thanks a ton Shubham. It means a lot 🙂👍🙏🙏

[@karthikeyanrm3446]

Yes please continue this SQL series - really good. If possible do resume Microservices section - it's pending for more than 2 months 👍

[@CodeDecode]

Yes karthikeyan due to time crunch and festive season it is getting delayed we will surely upload it soon...

[@rohinikumari4]

Hi I loved this video sooooooooooooooo much!!!! Please please upload the second part as I've been waiting for this kinda stuff for a long time.

[@CodeDecode]

Sure, we will upload it soon. Thanks 🙂

[@GamingPitchWithParth]

you are teaching in very good manner. loved your teaching style, keep uploading videos faslter ,it is helping a lot to me others thankyou.....

[@CodeDecode]

Thanks for the nice words sagar

[@bhavikjoshi1060]

Thank you for all hard work you put. Please cover triggers, partition, stored procedure and functions.

[@CodeDecode]

sure bhavik we will try to cover it soon

[@chaitalijuare6135]

Nice video mam. Please add more such videos on SQL. Will be waiting for your videos.Thanks for your efforts.

[@CodeDecode]

Sure Chaitali 👍🙂

[@sidhanshuraghuvanshi1]

If we have same salary then we should use GROUP BY Sal . It will handle duplicate Sal conditions also.

[@priyankapaul5620]

Plz make vedio on pl/sql stored procedure interview questions

[@dpkpk1573]

Thanks for the video....Nice one, Yes please make a continuation of this topic.....

[@CodeDecode]

Sure we will upload more 👍👍. Thanks 🙂

[@ahmadazeem7785]

You explain each and every concept so well.Thank you so much

[@CodeDecode]

Thanks ahmed

[@akshaykubade4210]

yes, plz mam make more videos on further topics of sql asap. It will be so helpful... and thanks..

[@CodeDecode]

Sure 🙂👍

[@anusuyadevi6256]

First I need to say thanks for such awesome videos in ur channel.Thanks a lot ..Please proceed to create more videos about SQL

[@CodeDecode]

Sure wr will do that👍🙂

[@jeevansaimanikanta782]

It was awesome explanation. Please do provide still more frequently asked sql questions.

[@CodeDecode]

Sure Jeevansai 👍. Will do that 👍🙂

[@vikassontakke4403]

Indexes are stored outside the table na?? Then how they can be deleted after dropping a table

[@harisharan4188]

Thanks for the Video, For the query to find Nth highest salary, I believe LIMIT will not work in all the DB's. Could you please explain using TOP too and is there any other approach too for the same?

[@CodeDecode]

Ok will give more such options in next video 👍👍

[@sachintambeshwar9712]

Amazing video to the point and various approaches to solve also 👍👍

[@CodeDecode]

Thanks Sachin

[@chaitutom5789]

Can u do one video on ajax calls jdbc drivers using java client and serverside validations

[@maruthikumar6811]

First of all thanks a ton on starting this SQL series. I'm expecting video on angular interview questions, Please try to do a video on angular interview questions

[@CodeDecode]

Sure we are planning to start front end iqs too 🙂👍

[@sreejak6776]

Tnx for the video

[@shruthishru3553]

wonderful video 😍..very easily understandable

[@CodeDecode]

Thanks shruthi

[@manoj47parmar]

Thanks for providing such video this is real helping me lot in interview preparation. Please create video on NOSQL db like: Cassandra,MongoDB also.

[@CodeDecode]

Sure Manoj, we are planning to do that👍👍

[@rudrapratapsingh213]

Hi, I was not able to find the best query for finding the duplicate records in a table, also to show how many times all the columns have been repeatedly stored separately , can you create a video in which there would be much advance questions? Also I randomly found your channel and it's very helpful, this time I am looking to switch the job and by god's grace I found your channel and videos are very helpful to me.

[@CodeDecode]

Thanks Rudra, yrs nice topics 👍will create video on this topic 🙂👍

[@vengateshm2122]

Thanks for the great effort. Pls put videos covering the question mentioned in the last section of the video.

[@CodeDecode]

Sure 🙂👍

[@user-yt5co6qq8w]

Hi, This is the wrong statement "Indexes with more than one column are called Clustered indexes". It is the case of the "composite index.".You can have only one clustered index in one table, but you can have one clustered index on multiple columns, and that type of index is called a composite index.

[@vaibhavnagrale8550]

Ma'am really appreciate your hardwork and efforts .. 👍 Please make more video regarding this topic ..

[@CodeDecode]

Sure Vaibhav, we are planning next part soon 👍🙂

[@darkresonance1541]

You Guys are awesome. It's day by day helping me to achieve my goal. Seriously, this channel is a gem and I've recommended it to my friends as well. I have one request, please make a video on real time scenario java interview questions. Like techno - managerial or client rounds mostly which will ask questions on scenario based. You're hell of a life & time saver. Bless you guys!!

[@CodeDecode]

Thanks a ton🙂. This means a lot us. Yes we are about to create a video on real time scenerios that are asked in interviews. Thanks for the suggestion 👍👍

[@AllinOne-et2on]

Truely you guys are producing an awesome content which help to crack interview easily.Till now did a great job and keep going ❤️❤️

[@CodeDecode]

Thanks a ton 🙂👍

[@kanhiyajoshi5346]

because of your channel , i am getting all interviews cleared.

[@CodeDecode]

Many many congratulations on clearing your interviews Kanhiya 🎉🎉🎉🎊🎊. You rock👍. Keep learning keep shining ⭐✨⭐✨ Man

[@saugatadey1248]

Yes we want more topics to cover...plss make a video...eagerly waiting.

[@CodeDecode]

Sure Saugata, we will do that 👍👍

[@srujan7350]

It is very good video to check out our Knowledge after learning. Thanks to #CodeDecode #Thanks

[@CodeDecode]

you're welcome srujan

[@Priyankapatel-zm2vq]

Your explanation is really good ❤❤

[@CodeDecode]

Thanks

[@MohitKhare]

thanks for the video.

[@CodeDecode]

🙂🙂👍👍

[@ravindracharyvadyarapu]

Waiting for next video ... kindly upload more videos on SQL

[@CodeDecode]

Sure ravindra we will upload the next part soon

[@rakeshkachhadiya]

Well explained.

[@CodeDecode]

Thanks

[@bhavinmajethia7070]

keep up the great work!

[@CodeDecode]

Thanks

[@AllinOne-et2on]

Please upload few more videos on SQL. Eagerly waiting for this videos

[@CodeDecode]

Sure we will create it soon.....

[@sunitapatil7394]

Please cover remaining....you are the best teacher. 👌

[@CodeDecode]

Thanks Sunita. Sure we will do that 🙂👍

[@AmitSingh-tk1il]

Awesome question collection

[@CodeDecode]

Thanks Amit 👍🙂

[@DivyaMahiChennai]

Ur video’s are excellent very useful 100% Please upload more videos

[@CodeDecode]

Thanks 🙂🙂 , sure 👍👍

[@jyothsnagangarapu1096]

super video ,could please create another video for other questions in sql

[@CodeDecode]

sure jona we will upload next video this week

[@shikshadubey4082]

Please add more series on most asked SQL interview questions.

[@CodeDecode]

sure shiksha you'll see next part in this week only

[@sarvan5002]

I expected few more SQL questions in this video, but it covered only two. if you can add more in ur future videos.

[@CodeDecode]

sure we will add more

[@qa8355]

Well explained 👍👍

[@CodeDecode]

Thanks 🙏

[@naleenyadav]

You are awesome..

[@CodeDecode]

Thanks Naleen 🙂👍

[@priyankasundar3497]

We more such fine tune and best practices in SQL

[@CodeDecode]

Sure Priyanka 👍

[@LaxmiKitchen]

Hi ,kindly cover other topics also and upload the videos very useful

[@CodeDecode]

sure laxmi we will cover it soon

[@KumarGaurav-xDsoCH]

First of all thanks a ton on starting this SQL series. I am expecting to refer only your videos, to brush up these topics. Waiting impatiently for next video 😁 Please help me in implementing Spring Security with OAuth 2 and JWT. Any references having flow the way you explain, will be helpful...!

[@CodeDecode]

These are very nice topics. Thanks for the suggestion👍🙂. We will upload these in security series 👍👍

[@mohitsoni2919]

Code decode is the best

[@CodeDecode]

Thanks Mohit🙂👍

[@VLearnAutomationLabs]

pl cover more ql interview questions and upload a video will be useful for us

[@CodeDecode]

Yes it's in queue 🙂👍

[@kudumulasivaramakrishnared6379]

Please do a video on tricky string interview questions

[@CodeDecode]

Sure 🙂👍

[@sushantsharma687]

Please create a video on some data structures questions

[@CodeDecode]

Sure Sushant 👍

[@neerajagarwal3176]

Please upload a videos for tuning of SQL queries.

[@CodeDecode]

Sure. It's a very useful topic. We will do that👍👍

[@tejachowdary309]

Please add more of SQL queries for interview

[@CodeDecode]

Sure we will create more videos on this

[@shylashreec388]

Please upload more videos on SQL.

[@CodeDecode]

Sure shylashree we will upload it soon

[@amitthakur-yo6xw]

Please make more videos on sql interview questions Mam

[@CodeDecode]

Sure amit we will create it soon

[@sivaramakrishna2602]

What if there are duplicate salaries ?

[@yashyadav5605]

For third highest salary What if highest sal is get repeated?

[@GrowwWithTime]

which editor you are using

[@CodeDecode]

IDE for sql you mean?

[@sudhanshuk.2627]

Mam please Cover more questions on SQL

[@CodeDecode]

sure sudhanshu we will cover it soon

[@chakradharchakri7827]

Part 2 or more videos from SQL

[@CodeDecode]

Sure 👍 we will do that🙂👍

[@swapnilkumar4157]

mam create more videos on sql pleaseeee

[@CodeDecode]

Sure Swapnil 👍 wr will do today🙂

[@humaripragati]

One correction-It is not possible to create an index on a view

[@rahulsolanki__]

Nice approach, But what if there are same salary for 2 employees , 1, Ram , 12000 2, Aksha , 15000 3, Manish, 12000 4. Ritu , 10000 5, Rohit, 8000 Here third highest should be 10,000 ie 4th row

[@CodeDecode]

No, when ever u sort in descending order, no one expects that. Even if they does, u can use distinct. Right?

[@alldemb9496]

select * from employeee where salary =(select distinct salary from employee order by salary desc limit 0,1);

[@ayyasamys1011]

Appreciate your work.. Can you please upload a video for apache shiro authorization using dB tables and spring boot ? It will be very helpful. There is no proper examples found in google

[@CodeDecode]

Sure 👍🙂

[@ayyasamys1011]

@@CodeDecode thank you

[@personxyz1840]

Is this mysql?

[@CodeDecode]

Yes