Boyce-Codd Normal Form (BCNF) | Database Normalization | DBMS

[@paulluke9460]

3 videos of less than 15 minutes explained my 1-hour lecture of 45 slides. Your work is amazing AND I LOVE IT!

[@Rajivrocks-Ltd.]

Amen! xD

[@Studytonight]

120 Likes to the comment. Wow!

[@sahil1053]

@@Studytonight 531

[@Subash-yw9js]

536

[@bernardobalixa4993]

45 slides, mine was 85 :| this videos saved me

[@JerseySlayer]

Everything you learn about databases is common sense. Then, they use 500 key terms and nomenclature and you forget what the hell they were ever talking about. Boiled down explanations like this are all you need. A 4 minute video that educates in a way I can't forget. Appreciate the video, a whole lot!

[@andrewschatz3949]

I spent 2 hours watching my professor's lectures, 1 hour reading the textbook, and 15 minutes watching your videos. Guess which one of those 3 was the most beneficial? I cannot believe how easily you explained it. You are truly a master of the world of databases.

[@DuyNguyen-hy1ox]

Nếu bạn chưa coi tài liệu tôi cá là khi bạn cọi video này bạn sẽ hỏi: primary key là gì? BCNF là gì? vân vân :)) . Chỉ đùa xíu thôi. Video rất dễ hiểu. Cám ơn tác giả rất nhiều

[@babajan5370]

same

[@babajan5370]

tomoroow my exam I seen these video my dobt will be clear because sir you explain one example

[@babajan5370]

and related on different topic amazing 😊

[@IqraKhan-fy8ot]

2025 walo

[@devpiush]

6 years later its still helpful to me for my college, thanks a lot !!

[@Studytonight]

You're very welcome!

[@dushananuradha1098]

I recommend this playlist for those who seek concise explanations on normalization relations. This lecturer has perfectly explained all the normalization relations around 5-6 minutes, whereas a typical SE lecturer would take hours creating a huge confusion.

[@Adam-ou1qp]

Oh. My. God. Thank you so much for actually keeping track of 2NF and 3NF and explaining them as you go along. I've found SO MANY examples where they try to show BCNF but the original table isn't even 2NF. Whoa. I can't believe it. It's taken me 3 days to find an example made by someone with a brain.

[@socratears]

When the video ended, I did not expect it to be *4 MINUTES SHORT*. You have me gaGGING at how incredibly simple and educational your videos are.

[@AadityaPrajapat-s8t]

2024 attendance here--

[@harshithpkcult3731]

May 1

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[@userlessx]

May 14, I have the exam in less than 2 hours...

[@alimansour496]

may 22

[@nanananaejm9278]

I tried to understand this with myself for weeks.... but you made me fully understood in 5 minutes. WOW

[@Studytonight]

Perfect!

[@muhammedaizazhaider8142]

Simply O MY GOD! spent 2 days understanding BCNF and this explained it in less than 5 minutes!!! can't believe. After all those non-sense bullshit with drowning into never-ending thousand's of key terms, composite, prime, super, candidate, alternate, foreign and loads of trivial non trivial dependencies, attribute closures etc. This lecturer is a GEM! U deserve at least a million SUBS!

[@Studytonight]

Hahaha! Thanks. Spread the word :)

[@lenubis1406]

Thank you for this, my professors keep using functional dependencies in (A -> B) form only to explain 2NF, 3NF, BCNF, and it gets so confusing, these vids were really helpful :)

[@priyanshudebnath1418]

Best video till now to explain normalization in the whole KZbin.

[@bhavyar2986]

All my 4 years of engineering, I have followed studytonight. I just love it. Thank you sir for this. You are amazing. YOu are awesome! Its amazing how we can learn so much from a free resource. Thank you A big thanks!!.. thank you * 100!

[@voxeledphoton]

Instructions were unclear my tables are now chairs.

[@Studytonight]

Hi voxeledphoton, What confused you and turned your tables upside down?

[@ash1800]

thank you very much 2 lectures 3 days study trying to understand but only ur 3 small videos works with me thanks a lot

[@fjm01]

The way you explained it, my professors never could! Brilliant work, Sir! Thanks a ton. :)

[@PegassiLampadati]

These videos saved me 2 hours of lecture time and 81 slides of powerpoint!

[@dam1433]

Almost four years later and this is still great! Thank you so much, this set of videos certainly helped me understand this somewhat dense material.

[@Studytonight]

You're very welcome! New video on Database Transaction dropping today :) Subscribe to the channel.

[@masonscott2125]

You, my man, are a certified legend. You got the gift bro. Thanks for the great videos!

[@Studytonight]

Glad you like them!

[@alishehzadpaul]

3:18 How does this table satisfy second normal form? Professor is dependent on subject, but not on student_id. I think it is a partial dependency.

[@_sowndarya.senthil]

(Student_id,subject) together determines professor attribute. This is known as fully functionally dependent And not partial dependency

[@-HarishkumarG]

@@_sowndarya.senthil but what's the use of having student ID inorder to determine professor ? Logically There's no link between professor and students ID. Please explain

[@aadjxx]

​@@-HarishkumarG Apparently, it's because a subject may have more than one professor. Subject alone is not enough to determine professor. However, I'd say it should make more sense if both subject and professor were part of a 'class' table, which would be then linked to student_id.

[@-HarishkumarG]

@@aadjxx thank you so much

[@yatmanwong1008]

ss_editz is right, because the functional dependency is professor -> subject, not subject -> professor. Given subject math you cannot tell which professor is teaching this student, there are many math profressors! Example like these are hard to come up, therefore just go alone with the fake business logic and just consider the functional dependency

[@shravanideshpande2058]

Amazing nf series, I had surfed entire yt but no other video could beat this. Here explanation is the fabulous

[@avishekgazmere6868]

These videos are so simple to understand. Thank you very much for putting this into the universe!

[@Studytonight]

Thank you Avishek. Share them around!

[@sumansarkar7842]

Thankyou!! Watching this video almost after 6 years of its posting date. Incredible explanation, is what I can say being a seasoned database implementationist. Good job!! 👍🏻👍🏻❤️

[@Studytonight]

Thanks 🙏🏼

[@Ayu-gj5pv]

Absolutely love these! They are short and not boring at all. Thanks mateys!

[@MrRavibains]

You explained these concepts better than anyone else out there

[@hugocontreras2848]

Dude you are my savior, I have exam in a few hours and this is just amazing

[@gajanparameswaran9947]

I think there is a partial dependency in the example : professor column only depends on subject not on student_id so it doesn't satisfies 2nd NF

[@friday7211]

I too have the same query, what did you conclude on?

[@sagarjain4128]

@@friday7211 Sab farzi hai 😂😂

[@sreekanththota2200]

Finally I understood Normalization By ur Valuable videos...

[@Bogdan-pf1om]

thank you, it s the first time i managed to understand the difference between 3nf and bcnf

[@thedevonaitor]

Great video, the claps at the end startled me lol.

[@rajkumarmeena7369]

Your videos are good as they explain these concepts with solid examples. One thing you can improve upon is to also explain why it was necessary to convert the table into BCNF. What was the problem with table before converting it into BCNF?

[@aniknarayan1692]

I wish KZbin allowed us to Like a video multiple times... Every time I watch this for revision I feel a strong urge to click on the Like button again 😁😁😁 Great work, keep it up 👏👏👏

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Welcome to KZbin university, where complicated things from school makes it less complicated.

[@shivamghatak86]

Study tonight is my favorite website

[@metehanemir7454]

4:09 Isn't there Transitive Dependancy now on the right table? Since Subject is functionally dependant on Professor (Professor implies Subject, proof @ 3:07), and both are non-prime attributes. That would mean that it isn't in 3NF, which means that it also is not in BCNF.

[@metehanemir7454]

Either that or I've gotten the definition of transitive dependancy wrong. May someone explain why there is no transitive dependency in the last right table? Thanks.

[@star_types]

thanks... while everyone is just teaching B must not depend on A and blah blah... you explained like a pro...

[@himanshusrivastav3695]

Sir I have no word explained about your video amazing video

[@Alazer-uh6gq]

I have no words . Much respect👏

[@Iceworld29]

6 Years and it's still helpful

[@sodiko100]

How is there no partial dependency ? Primary Key is {student_id, subject} and Professor relies on only part of the primary key which is subject. Professor should not be included in the table due to 2NF

[@BatVal]

How is there no partial dependency when professor is determined on the subject, but not the student_id and subject is part of a comp key?

[@sodiko100]

The example is wrong. There is partial dependency like you said but also subject is not a prime attribute. It should be split into more tables due to 2NF

[@jl12-tt]

was confused by that too

[@jl12-tt]

Maybe 1 subject can have multiple professors?

[@aswing2706]

No, the subject alone cannot uniquely determine the professor. There are different professors for the same subject, like Pjava,Pjava2 for java subject. Only student along with subject can uniquely identify professor. So it does not have partial dependency ,so 2NF

[@voon2770]

An hour before exam, thanks for simple explanation

[@blaze9558]

watched many videos this one was on point. thanks man

[@Studytonight]

Glad you liked it!

[@nishitasinha6048]

How will it be in 2NF? Professor is only dependent on SubjectId and not StudentId.

[@Huhwhatt]

I have the same doubt, were you able to figure it out?

[@Huhwhatt]

oh never mind, I got it. A single subject can have more than one Professor. So, we need both student_ID and subject to figure out professor. So, no partial dependencies!

[@AdityaKumar-mt1rh]

consider stdid 101 you will get your answer ;)

[@jaiswaljitu]

@@Huhwhatt thanx

[@simplymade7802]

Parth Patel yes that's right one subject may have more then one proffesor but it is not specified that students are divided into groups and one teacher is allocated to a group and second to other. If it would be the case then proffesor depends upon both student-id and subject-id and there would not be any partial dependency...but it is not the case..so proffessor dependes upon subject_id only... I think..

[@mariojosuecastro303]

Pretty simple and straightforward. Thank you so much!!!!

[@makinenivanshita1292]

You saved so many lives!

[@amanarora8746]

How is the table given at 3:24 not partially dependent? like the professor name only depends upon the subject id and not on the student id so that will definitely cause partial dependency to exist.

[@danawang780]

the professor name depends on both subject_id and student_id in this example, because we assumed that multiple professors can teach the same subject. Therefore given only a subject_id, we can't be sure which professor teaches it.

[@devanshuraj8413]

@@danawang780 even if multiple professor can teach same subject how come professor get dependent on student? @StudyTonight

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East or west but SIR you r the BEST

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I like your voice...... finnaly i got a good lecturer🙂

[@AKSHITH_SHELBY]

bro tmr is my exam it is very usefull for my sem bro thank u so much bruhhh🤗🤗😍😍

[@Studytonight]

You are welcome and glad this video helped you. I hope you scored well in he exam.

[@urjamishra6419]

Bhagwaan ho aap! Seriously god!!❤️💯🔥 Thank you so much for these videos sir! They are so so easily explained! I just can't wait to see this question in my tomorrow's dbms exam! And fill the paper as fast as u taught me! I hope to learn more from you!⭐ Keep going!!!!

[@Studytonight]

We all are learning and teaching others is the best way to understand things in a better way yourself. Do subscribe to our channel for more videos.

[@umarshuaibu2077]

What a nice explanations. Thanks for saving my life oo

[@Studytonight]

Thanks for your comment :)

[@mobeenahmed2916]

Please do a video about tables relationships in a DB You explain so good 👍

[@prakharjaiswal5774]

bhai baap explanation in less time😁

[@Studytonight]

Thanks bro. Glad you liked it.

[@mrk131324]

It is worth mentioning for the example that we assume that each professor only teaches one corse, otherwise the deconstruction would not work.

[@Studytonight]

Noted! and thanks for mentioning this.

[@aadjxx]

Yup, I was questioning the same thing. Thx for clarifying.

[@aadjxx]

I double checked and it is actually stated in the video. Briefly, but it is there.

[@neonmusic7028]

You are born for teaching . Really good videos :D

[@sanjanayadav6360]

The series was awesome and helpful. Thank you.

[@codewithme3548]

Very Quality content. I wonder why did you guys stop making more videos. Very clean, simple and nice explanation.

[@samsonM08]

After BCNF, in table 1, Pid is not dependent on Student Id, so table 1 voids 2NF rule.

[@KenriHayashi]

6 hours of lectures compressed in 4 videos... and this one is easier to understand too

[@dagimbbekele1771]

thanks, this is special video on normalization

[@baqirhusain5652]

Question Are the decomposed table in bcnf? I dont think so bcos even now Professor->subject Non prime->non prime Transitive dependency? Please explain

[@Studytonight]

Well, when we break the table P_ID is more like a representation of the relationship between Professor and Subject. Each P_ID will have a unique combination of Professor and Subject against it where may be a Professor teaches more than one subject and may be a subject is also taught by more than one professor. Hence P_ID will be the deciding factor or we can say the prime attribute in the broken down relationship. Hope it makes sense.

[@gurkandemir1643]

Studytonight But, according to your explanation you said, in the last versiyon professors have a right to teach more than one subject. However, if so in the first table there is no functional dependency between professor and subject since professor teach more than one subject, which means first version is also bcnf?

[@Studytonight]

@@gurkandemir1643 Yes, true. When we say that each P_ID will have a unique combination of Professor and Subject that means, "Prof1"-"Java", "Prof1"-"C++", "Prof1"-"Python" all are unique combinations as the subject names are different. Hence, one professor can teach more than one subject.

[@lavanyam1511]

@@Studytonight But you said in the video that each professor teaches unique subject. If multiple professor can teach multiple subjects then the problem of bcnf wouldn't have been arised!

[@ammarhaider1530]

After converting to BCNF isn't there a transitive dependency in Professor table (p_id -> professor - > subject).

[@jaideepshekhar4621]

I think no, as the names of two teachers can be the same, and therefore you cannot be sure which teacher you are referring to. But the professor ID will be unique for each professor, and you can find the name and subject from it. But... this also means that the table was in BCNF at the start, as you cannot uniquely determine subject from professor!

[@CreeperHaunterDavid]

i was thinking the same thing

[@thebipulkumar]

How does this table satisfy the second normal form? Professor is dependent on the subject, but not on student_id. So, It doesn't No fulfill partial dependency. Hence not in 2nd normal form.

[@chethaspyla3108]

no because there can be different professors for the same subject

[@saiajay696]

this tonight channel is making my tomorrow's exam simple.

[@logbasex826]

How easily you explained it. Brilliant! Thank you so much

[@neil_from_future]

So I paid 200$ just for a 3-hour class where this 20m part got explained in this video in 4m. Huh wth I'm doing with my life

[@takeadecisionupwork3772]

I understand as a teacher how much effect u put for this lectures in simple way

[@DAPHindiGaming]

For a Database to be in Boyce codd Normal form two condition must be satisfied: 1. It should be in 3rd Normal form 2. There should not be a dependency A->B such that, A is a non-prime attribute and B is a prime attribute.

[@akshaychopra96]

Amazingly explained :) Post other videos soon. My exams are from next month. Waiting!

[@isaiah2810]

@ 2:44: “In this table, the student_id and subject forms the primary key, because we can use student_id and subject together to find all the other table columns. . . .” How can you use student_id and subject to find all of the entries in the Professor column if you have two professors that teach Java? It would be impossible to know which of the two Java professors the student has.

[@ShivaKumar-dj8bj]

Hey, Nice question. If there are multiple professors teaching a subject then the Professor should depend on both subject and student( class would make more sense). does it answer?

[@subtainabbas1867]

at 4:09 in professor table, again subject can determine professor(transitive dependency)! isn't it?

[@poojashettyrs6132]

Thank you soo much for this great job..you explained it in such a manner that anyone can easily understand..we expect more and more videos related to cs

[@davidnguyen9023]

Thank you so much for this series!

[@robarntz4916]

Hi there. In the final example to BCNF we can have (Student1, Teacher1) and (Student1, Teacher2) and (Teacher1, Java), (Teacer2, Java). This will imply that Student1 foloows Java twice (once with Teacher1 once with Teahcer2). I think this is not correct as the original table had a unique key on the combination of Student and Subject so the combination of Student1 and Java must be unique. Or am I missing something here?

[@keshavbrambhatt]

right

[@be-yo-nd-all2637]

Great content and consice information. Thank you

[@PremjitSingh03]

Hi, thanks for explaining it very clearly. I want to point out that the CollegeEnrollmentTable is NOT in 2NF since the column Professor is only partially dependent on the Subject and not the studentID. So in my view it's not a good example to explain BCNF. But if you group all the 3 columns and consider it as a primary key , then it's in 3NF since the table has no non-prime attribute.

[@dunlopgator1539]

Professor is not partially dependent on Subject. Subject does not derive Professor, since a subject can be taught by many professors (Java - PJava1, PJava2). Looking at a subject, you cannot tell exactly which professor it is taught by, since there are many.

[@sumitsaha6941]

@@dunlopgator1539 thanks it's really helpful❤

[@productivityaccount8274]

Loved it❤️

[@bondipavan9276]

Sir really awesome sir I can understand very simply sir. Thanks for bring these type of videos for us sir. We wish that as soon as possible u will want to be in high....

[@dunno418]

⚠I feel the new professor table can be not in 3NF and BCNF because P.Java2 can determine what the P.id(violates BCNF) can be and also the subject it teaches(violates 3NF). The example instead of using "P.Java2" as a name should use for example "ABC" as a professor ABC can teach Java2 or maybe English_1 or whatever this makes the example more life like 👍, as ABC can not determine the both. it seems a little weird a professor having two id's but not at the cost of violating the two forms. (composite key makes sense here) another design could be using extra column for a professor (if they want to teach extra subjects) but seems like it would create variables which wont be occupied ( i dont know how space is utilized in NULL places in RDBMS) @Studytonight watch this please, and thanks for this amazing tutorial one of the most consistent lectures i have seen. EDIT: OH WAIT i just realised my design suggestion would lead to violation of 2NF (only professor enough can determine other two subjects in seperate column (maybe)), of 3NF( if professor isnt primary key or part of composite) and of BCNF(as professor name can determine their ID 😭. The above composite primary key example is much better 👍

[@sebon11]

Super cool, haha this way of educating is sooooo coool

[@MartinHusak]

QUESTION: Lets assume that single professor can teach multiple subject. Would it mean that the original table / model was already in BCNF ? As this split to 2 table would not be possible, right ? More importantly the (student, subject) will not guarantee the path to professor, right?

[@techvishnuyt]

thanks for the explanation, that was quick and time saving thank you

[@Studytonight]

You're welcome!

[@ajithnandagiri9463]

God of dbms @studytonight

[@brucelamb6060]

Is there another video that explains BCNF? The 1NF, 2NF, 3NF vids are superb! Thank you

[@Studytonight]

Let me see what can be improved in BCNF video 😊

[@nilotpal8327]

sir make videos on "Transaction and Concurrency control" and other DBMS important topics too. your way of teaching is exceptional.

[@avaz7939]

In the professor table, we can also use subject to find p_id, then it will also be a non-prime to prime. Do we allow this in BCNF?

[@hemvjay]

There can be same subjects with different pid

[@alroyloh9135]

your videos helped me out a lot, thanks so much. Super easy to understand as well :)

[@subalchatterjee6641]

Awesome Job!! Please carry on the good work..

[@arunjose95]

Having a confusion in the approach to convert the table to BCNF. In the professor table 4:09 there are columns for professor and subject, as the subject is dependent on professor isn't this a transitive dependency ? So why wouldn't it violate 3NF?

[@jahnavireddy5127]

I have a doubt.. I think removing subject from student table is meaningless.. Because each student will be having many subjects..and therefore there will be many professors associated with that record..not just one.. Then how to break the table? Should we have to use all the 3 attributes to uniquely identify the row??

[@zss123456789]

I have doubts, too, but for different reasons. To accommodate for multiple professors, you would make both student_id and p_id primary keys so you can have multiple records for the same student. But this set up assumes each professor only teaches one subject, which we know is often not the case. Associating just the professor with the student won't tell you which subject the student is taking if the professor does teach multiple courses. It sounds like you will end up with a 3 way many-to-many relationships. (A student can have multiple subjects and professors, a subject can be taught by multiple professors be taken by multiple students, a professor can teach multiple subjects and students) I think it makes more sense if the table is left unfixed.

[@sheepnoisebah]

you mean this? PK: primary key, FK: foreign key 1st situation: PKstudent_id, FKsubject_id PKsubject_id, subject_name, FKp_id PKp_id, professor_name you end up only having 1 professor per subject or 2nd situation: PKstudent_id, FKp_id PKsubject_id, subject_name PKp_id, professor_name, FKsubject_id subject name is unique so there's no real need for subject_id, so you end up like in the video: PKstudent_id, FKp_id PKp_id, professor_name, subject_name

[@amritadas3743]

in short this video is realy amazing. keep it up!

[@e.s298]

simple and clear , thanks

[@varadsinghpardeshi7971]

we can also look at it as partial dependency right...? and add professor to the subject table.... can't we..?

[@Studytonight]

Yes, we can.

[@Lallu-gv9rs]

Hello can you please explain what you were talking about? Thank you.@@Studytonight

[@martinfischer8798]

Can anyone explain me why the last tables are in BCNF when the subject is still dependent on the professor? Don´t we have a transitive dependency here?

[@sharks445]

Subject can be taught by multiple professors, but professor can only teach one subject. Therefore subject is not dependent on professor

[@vishnus2567]

in last, when we split the table in to student & professor, the student_id in student table is not unique ?🤔 because a student is taught by multiple professor? Then how student_id can be a primary key ?

[@AnilKumar-ve2yl]

sir i have one doubt that does super key contains only prime attribute? if yes then it means if our prime attribute is dependent on prime attribute then is it in BCNF??

[@abhinavarya7752]

Just think after 100 years, our son and daughter would have to study and remember 1000 normal forms. I really feel sad for my upcoming kids in future.

[@HarshaArtWorld]

At the last where it comes the professor id ? When we divide the table

[@Rajivrocks-Ltd.]

You make it up because without it you can't make it BCNF compliant.