3.12 Finding Number Of Candidate Key

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[@ashutoshdixit2806]

hukum ka ikka boss

[@mohitchhabria4014]

Sir in 3rd example at 12:00 only B should be the candidate key na?

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kya flow he sir aapke padhane kaa maan gaye. really appreciable

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Excellent Session and very good tricks to learn to find candidate key!!

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You have such a happy face sir. Keep smiling and keep helping us

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[@AnubhavMadhav]

In example 5, only 'B' is the candidate key, as it is the only essential attribute and closure of B gives us the complete relation too. And any further key, is just the superset of it. Please verify!! Thank You so much Sir!! You are the Best!! See, you made me an expert in this I guess. 😄

[@badalkamli7816]

That's what I was wondering about

[@debasispattanaik1724]

Sir. .. excellent...I had doubt...but 100% clear... thank you sir...

[@rohan8758]

@20:40 in the question 6th, C.K-> {y, wx, wz} you have told but candidate key definition is minimal super key, According to this def.. C.K->[y] only. If i am wrong then correct me..

[@chintangaur2306]

same question...

[@delhicitizen6396]

Y wx or zx ka part nhi he wo unique he .. isliye wo bhi c.k he

[@er.govindnarayan7526]

Well explanation sir. Thank you.

[@ravi090ravi]

After watching 7 bookish-languaged videos, this is finally the "Bhramastra" video... All concepts Crystal - Clear... Thanx a lot

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[@siddhant2943]

In example problem 3, R(ABCDEF), relation R could be functionally determined from attribute B alone. B must be the only candidate key for the relation. Please verify.

[@Pradeepkumar-kq7bj]

sir you are great teacher pls upload more videos reletional calculus

[@varunpandey9786]

To find essential attributes....we can also check on the left of all relations & see which attributes are not present there in the given relation

[@rajkumarsingh1473]

in 4th q (16:22) the candicate key willbe B and D by b we can go to cd and using c to a and by D we can go to b so it will be also a ck

[@abantyring732]

Sir ur effort is colossal, pls if possible teach us some more examples with complex one.

[@arpanmondal4979]

Sir aap itna achcha kaise padhate hai... kya hold hai apka subject k upar!!! Kash aap mere college k teacher hote...Toh padhne mein maja aa jata

[@nipunkumargoel7644]

best DBMS tutorial. Thank you

[@ankitmehta4133]

Thank you. Now I can find Candidate keys. Just because of you.

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[@makjamia08]

Relation R has eight attributes ABCDEFGH. Fields of R contain only atomic values. F={CH→G, A→BC, B→CFH, E→A, F→EG} is a set of functional dependencies (FDs) so that F + is exactly the set of FDs that hold for R. Q.54 How many candidate keys does the relation R have? (A) 3 (B) 4 (C) 5 (D) 6 Q.55 The relation R is (A) in 1NF, but not in 2NF. (B) in 2NF, but not in 3NF. (C) in 3NF, but not in BCNF. (D) in BCNF.

[@rohitverma4449]

I love....... your vedios... Sir..... Ji........ Sir please make more vedios on tough questions to find candidate key 🙂🙃

[@c.danielpremkumar8495]

9:04 how can BD be a candidate key ? Because to get D you need both A and B. B alone cannot find D.

[@anushkashankarsrivastava6681]

BD= DB(itself) A(D-->A, also BA-->CD and D has already occurred once) so BD= BDAC

[@surajsharma939]

YOU ARE RIGHT

[@Karthikhebbar4]

@@anushkashankarsrivastava6681 Thanks!

[@Anupam1782]

sir,please provide some more questions related to finding a candidate key. thanks

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[@anjaliverma905]

Sir in question 3 B would be candidate key , ( BF ) wouldn't be a candidate key nah ????

[@sarthaknirgude]

No,F is essential attr. so we need to consider F ,If we only consider B then (B)+ = ABCDE here F is missing hence B can't be C.K>

[@varunyadav-zp6pw]

awsome teaching style.. Best Video Tutorials on dbms

[@rozinanaz1907]

Sir you are excellent... The way of explanation is really very nice... I was never ever interested in these topic but only because of your teaching this has become a much more interesting subject for me ever

[@RealZephyro]

absolutely lovely video and thank you very much for helping us and taking so much pain for us ♥️

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[@Harshita_Bhardwaj]

Thank you sir very informative interesting and detailed video!

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[@Harshita_Bhardwaj]

@@KNOWLEDGEGATE_kg Absolutely Sir. Thanks a ton again😃

[@jyotisawakare862]

Excellent video... thanks a lot for taking so many examples.

[@shreyagupta9643]

Sir I like your tricks

[@exampoint678]

One of best lecture 🙏

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[@shikshitkumarverma4298]

Thankuu so much sir for making this video for us

[@48_subhambanerjee22]

Sir this is easy, but i found some questions where there are no incomming edge but still candidate key, like R={A,B,C,D,E} FD={A->BC, CD->E, B->D, E->A} Here no attribute have incomming edge... Still A and CD are candidate key

[@KNOWLEDGEGATE_kg]

Dear @Shubham, In the context of functional dependencies in a relation, a candidate key is a minimal set of attributes that can uniquely identify a tuple (row) in the relation. In other words, a candidate key is a set of attributes that functionally determines all other attributes in the relation. In your example, the relation R has the attributes {A,B,C,D,E} and the set of functional dependencies FD={A->BC, CD->E, B->D, E->A}. From these functional dependencies, we can derive the following additional dependencies using Armstrong’s axioms: A->D (using transitivity: A->B and B->D) A->E (using transitivity: A->D and CD->E) A->BCDE (using union: A->BC, A->D, and A->E) This shows that the attribute A functionally determines all other attributes in the relation. Since A is a single attribute, it is also minimal. Therefore, A is a candidate key for the relation. Similarly, we can derive the following additional dependencies for the attribute set CD: CD->A (using transitivity: CD->E and E->A) CD->B (using transitivity: CD->A and A->B) CD->D (using reflexivity: D->D) CD->ABCDE (using union: CD->A, CD->B, CD->E, and CD->D) This shows that the attribute set CD also functionally determines all other attributes in the relation. Since there are no smaller subsets of CD that can functionally determine all other attributes, it is also minimal. Therefore, CD is also a candidate key for the relation. The concept of incoming edges is related to the construction of a dependency graph to find candidate keys. In a dependency graph, nodes represent attributes and edges represent functional dependencies between attributes. An incoming edge to an attribute means that there exists a functional dependency where the attribute is on the right-hand side. In your example, even though there are no incoming edges to any attribute in the dependency graph, we can still find candidate keys by analyzing the functional dependencies and applying Armstrong’s axioms as shown above.

[@48_subhambanerjee22]

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And sir I will tell my friends about you too sir. You are the best teacher ❤️

[@shwetaasingh4807]

Awesome video... Don't have words

[@pratikaagnihotri2346]

wow sir, you are amazing. What an explanation...

[@nischalpokharel1910]

in last example BDE D gives AE then AB gives C then E can give F then all are derrived but why it cant be closure

[@hangsajyotidhar9696]

DC gives AE

[@rishabmudliar1058]

Watching this a day before my DBMS exam :)

[@Ankit-we8ym]

thank sir I watch all your videos and recommend everyone who is studying computer science and can understand hindi.

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Best explanation till date👌👌

[@kanishksharma2139]

sir thank you so much for providing these lectures...u r the best teacher for me... thank u so much.

[@sayanisen8072]

Do u have any more video on candidate key identification ? Plz share the link

[@NikhilKumar-th6yj]

Sir in example 6 W can also be in that key?

[@anubhavnegi7428]

Very well explained sir.

[@vaibhavkumar4951]

at 10:01.......if we add A in BC then it will become ABC....... through ABC we can find the whole relation........ and through BC we can not find the whole relation....... so BC is not a proper subset of ABC......... so i think ABC should be the candidate key........ please solve my doubt sir!!

[@vaibhavkumar4951]

sorry, sir aa gya samaj me......

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Hates off to you sir, you are an amazing person. Thank you so much for these videos. From Pakistan.

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Sir your video make our day's Thanks a lot

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Thank you sir!! You're a gem

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Your videos are awesome sir....🙏

[@gollasaivenkatesh]

nice video ,we can write algo for finding this using your logic

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[@priyeshprince2318]

Thanks sir for your kind support for us and sure upload another video with some trickey questions

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Thank you so much 🙏, best explanation i found on KZbin 🔥

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best teacher

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Thank you so much for considering that.. keep supporting and sharing videos with your friends so that I can help more and more people..

[@akashshirale1927]

in question number 6 ::(WZX) will also make a candidate key ....wonderful video learnt a lot ..thanks..

[@namankhard4270]

WZX will be the super key since XW or XZ are the candidate keys augmenting any other attribute to candidate key will make super key

[@jeetendrayadav6257]

Love you sir Ji for your dedicated efforts

[@harshilshah2507]

superb work bhai!!!

[@makjamia08]

Candidate key ka 2nd question samajh m nahi aaya... BF kaise candidate key ho gaya.. Usk baad combination lene ki zaroorat kyu nahi h???

[@poojabindlish4615]

U r grt sir. Its totally clear...tysm

[@SumanKumar-ds7hl]

sir,in first question ABC is also a candidate key ,because there is no proper subset of ABC?

[@AnubhavMadhav]

No bro, ABC is not even a key, because you cannot find the complete relation (ABCD) using closure of (ABC). I hope you got it.

[@ayushiagarwal528]

In example 6, if we are asked about minimal candidate key, what will be the answer? 1(i.e y) or 3(all cks)

[@AshishYadav-fi2zf]

i m also confused ....

[@ayushiagarwal528]

If you get to know please let me know too

[@AshishYadav-fi2zf]

ohk sure... but sanchit sir is more intelligent then me...

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My day starts with colgate and ends with knowledge gate:)

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[@udaygupta929]

BD cannot be a candidate key using B I cannot C and using D I can access only A and from A I cannot access C but using AB

[@delhicitizen6396]

Yes it's question no. 2...BD is not super key

[@vanshikapatel949]

In example 6 Y is the closure attribute and it gives the R then why we need to find closure of wx and xz ??

[@sarthakjoshi21]

amazing sir

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[@askariaziz4163]

thank you for the special videos

[@SaiKiran38252]

Awesome

[@ThePRINCEBARPAGA]

10:39 ahahah so funny F bhaisaab participate hi ni kar rahe...

[@meeninathdhobale7154]

sir you are great. thank you so much.

[@kookaburra2374]

How to find CK's if there is no FD's???

[@NishaSharma-nd1dk]

Thanks sir g

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Welcome

[@akshatakasar1997]

Please sir make videos on Elements of number theory .

[@eaditvideocreation1887]

Thanks a lot sir your teaching performance excellent

[@KNOWLEDGEGATE_kg]

You're welcome, keep learning! You can also check out our website www.knowledgegate.in for more videos & contents👍

[@kshitijkumre9895]

14:25 you've made a MISTAKE. 'AD' is not the key. You cannot get all tuples of the relation from 'AD'. PLEASE CHECK IT.

[@kshitijkumre9895]

MISTAKE .................. 14:25

[@VideoLanxer]

He has ability to use more than 10% of Brain power !!

[@PANKAJKUMAR-uk3uo]

and what is composite key?

[@gurmailsingh792]

sir 4th example me AD and BC kaise key ho sakta hai ???????? because with only A we cannot find C and in case of BD how can we reach to C???? Please explain Sir..... Thanks

[@Harendrasingh-op3lv]

in case of (AD)+ = (A,D already exist D->B so B also exist so (AD)+ = (A, D, B,... now AB -> CD => AB->C,AB->D(decompositon property) so (AD)+ = (ADBC);

[@Harendrasingh-op3lv]

Same in case of BC;

[@sravani9595]

@@Harendrasingh-op3lv tq sir now I understood it well

[@Harendrasingh-op3lv]

@@sravani9595 welcome 😊 .by the way I am not sir.... currently in 3rd year

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@@Harendrasingh-op3lv hoo kk

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Superb Sir

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Please give some more example to work for net exam

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3rd example really awesome

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Har kisiko aane ka moka milega. If you watched class attentively you will get it

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hats off to you sir

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Thank you so much sir.....

[@CuriousGirl-g2g]

Thank you sir.

[@lsuremusic3787]

Awsome.. Thankuvsir

[@krupaparekh6239]

sir can you tell me what is exactly schema means? because i am very confused about it and i can not understand it by definitions..

[@alokagrawal2545]

krupa parekh In simple term ,schema means table.

[@AshishYadav-fi2zf]

sir..example 6 mein 1 hi candidate key honi chahiye..

[@sravani9595]

Ss I too think the same

[@aviksarkar707]

Y has the capability to identify all other attributes, so our motive should be to find Y. WX-> Y can identify Y trivially, so WX is a candidate key. Z - > W, so XZ can identify W and WX -> Y, so XZ is a candidate key. Total 3 candidate keys - Y, WX,XZ

[@PrashantSingh-oj5ez]

no we have to take all possible combination

[@amrutabagalkot6407]

Sir pls explain how to find candidate keys when FDS are not given