Lec 17: Dependency Preserving Decomposition in DBMS | Practice Problem

[@farahsultana1988]

In first problem R(A,B,C,D,E) F:- {A->BCDE, BC->AED, D->E} is given. i.e. {A->B, A->C, A->D, A->E[Decomposition rule] BC->A, BC->E, BC->D, D->E} Now R1(A,B) , R2(B,C) , R3(C,D,E) is given. For the relation of R1(A,B) A+ = {A,B,C,D,E}. Here A is reflexive and trivial so A will be discard C,D,E are not belong to R1 sub relation so . .. C,D,E will also be discard . As a result A->B. For B+ = {B} since B is reflexive. and will be discard. So no determined by B. Therefore A->B only from R1(A,B) . Now from R2(B,C) B+={B}. Nothing from F dependency and B is discarded since reflexivity. C+ = {C} only and discard. So no relation comes from R2(B,C). Finally from R3(C,D,E) C+={C} discard . D+ = {D,E}. D is discard. And D->E. E+ = {E} is Discard. Again CD+ = {CD,E}. CD will be discard by reflexivity. And CD->E. Again DE+ = {DE} will be discarded for same reflexivity fact. Here D->E in the R3 relation . So CD->E is nothing but the duplicity of a common determination. i.e. D->E. So CD->E will be discard logically. Now the Partial functional dependencies come to G as : A->B, D->E . Now Check if G Covers F or not here Directly G covers F. Because in G : A->B and in F: A->B by decomposition rule and D->E also exist in the F dependency. Now recheck that F covers G or not . In F A->C, A->D, A->E are not covers in G Dependency. And F's D->E matches to G dependency. So it can be conclude that F does not Covers G . So these relation is not Preserving Functional Dependencies by Preserving.

[@negarmahdavi4330]

G doesn't cover F but F covers G because G is driven from F.

[@victorychannel2952]

Can you please tell me how they are dividing a relation r into sub relations r1,r2,r3 is there any rule to consider

[@subratamandal2924]

@@victorychannel2952 that will be given in the question. You just have to determine the fd's of the subrelations

[@rageshor1772]

1'st question: not DP 2'nd question: DP Ma'am your class verry usefull,.💯💯💯💟💟 excellent teaching💯💯😍😍💕💕👍👍, please upload more videos in DBMS, Computer Organization

[@novicecoder5753]

Same

[@karthick2523]

same

[@pratham8275]

Got same answer on 13.05.2024

[@avinashkariya6635]

After 2 days I've exams, and I can proudly say that by watching your videos, I'll be clearing out my dbms paper firellyy. You're great

[@soumyamitra7831]

E. A. Codd is the father of DBMS. But you are Edgar Frank Codd for me and others like me. Lots of Respect and Love. I will definitely meet you someday. Love from West Bengal.

[@stackritesh]

I've my exams in next week and i've cleared approx everything. i looked upon the P.Y.Questions and now i can solve it and score good marks in my upcoming sem exam thanks a lot mam ❤❤. best thing is you also give practice questions which makes the understanding of the concept better. you've taught each thing in a very clarified way. Thanks again :)

[@nikhilkumarsingh6385]

Date - 21/09/24 Question 1 answer - not depending preserving decompostion Question 2 answer - depending preserving decompostion Thank you so much ma'am ❤❤🎉🎉😊😊

[@balasubramaniantk4863]

Mam you rock, ❤️❤️❤️❤️💐💐💐💐 Always my secret potion of knowledge...

[@rayDJ.AbdNas]

lol your videos are coming in clutch right before my exam... If i have to resit I'll definitely be using your videos to revise... Wasted tens of hours on my uni lecturer notes, understood concepts from the lectured that took up to 2 hours to cover, and yet not understood well, in less than 15 minutes with your videos 🔥

[@rishiranjan1119]

Ma'am please start Computer Organization & Architecture series...

[@ahmadshafique8453]

Thanks so much as she is very good explain points to points and last. I say that I very understand to every topic and my wish that you are teaching to always Be happy and keep smiles

[@petarpartaloski8889]

Big thanks from Macedonia! Keep up the great work 🇲🇰 💛❤️

[@ArronSton]

Ma'am you're so cute even i don't have any exams but still i watch your every video daily. And thanks ma'am for providing this content for students like us lots of love from us 🥰🥰

[@millionplusviews8013]

1st Que is... Not Dependency Preserving.. 2nd Que is.. Dependency Preserving Very Thankx Maam... 💞💞💞💞

[@ankitakarmakar1114]

I really like your videos, you explain everything very well! Please start off with Computer Network lectures asap.

[@Pankajkumar-gh8su]

So cute mam 😍😍😍😍 me aapke is exam se judaa huyaa nhi hu but fhir b aapko dekhnee aaa jaat hu yhaaa or like krke jaata hu mam 😍😍😍 u do very gooooood veryyyy goood work god bless u dear😍😍😍

[@chandrapydikumar8343]

now we have DBMS in 3-6.it is very helpful to me thanks a lot

[@debajyotideba5001]

Please don't dislike my favorite Mam's video... She worked hard for us...

[@priyankapaul7077]

Madam, you decomposed the relation in 3 but in exam the decomposed relation will be given or I have to create it by myself?? 18:31

[@shyamkedia4202]

Last semester DBMS is over ...now I want to study it again😍

[@seemadahiya432]

Fst ques not dependency preserving 2nd ques dependency preserving. Plzzz mam tell I m right or wrong

[@udayabhi185]

Yes My answer is also same

[@rajarshibasu6436]

Got the same answer thanks for sharing, for more clarity I'll write down the FDs of the sub-relations in each question (open to discussion): Q1. f1 : { A -> B }, f2 : {}, f3 : { D -> E } ..... F is not in G (= f1 U f2 U f3). Q2. f1 : { A -> B, B -> A }, f2 : { B -> C, C -> B }, f3 : { C -> D, D -> C }..... F is in G (= f1 U f2 U f3).

[@gihandbandara-chemistry2927]

yes my answer also same

[@kavyajayesh7665]

My answer also same

[@JoffreyB]

8:12 you’re saying that CD->E is duplicate because you can derive E from D already in a previous FD. But with that logic D->E is also a duplicate, because you can derive E from C using C->DE (C->D, C->E). Or I don’t understand something? Please explain this moment. Thanks for the videos!

[@codebreaker8928]

If anyone who has this question C-›de ,c-›d n c-›e but d-›e reverse and it is not possible we can derive d using c but we can't go in reverse order n we can derive d-›e since they r on same side ie from c-›de, d-›e is not possible

[@somaysharma193]

Following u from Poornima University 👌🥰

[@yon1623]

you explained this 10 X better than my teacher now about to share it to everyone in the class discord

[@kumarayush9499]

Thank you maam, very easily understandable lecture.

[@ranjithkumarc2710]

I have stepped into next level of DBMS thank you mam

[@vinitupadhyay8101]

Closure of c in R2 would be c-> AEDBC (from BC->AED) , so FD : C->B

[@karandhar316]

How can we determine the appropriate number of subrelations needed when decomposing a relation during normalization?

[@FINANCIALYOGI]

Answer to queries: First answer R(ABCDE) FD(A-BCDE, BC-AED, D-E) R1:(AB), R2(BC), R3(CDE) decomposition not dependency preservi g. The next R(ABCD) FD(A-B,B-C,C-D,D-A) R1(AB) R2(BC) R3(CD) this relation and it's decomposition is dependency preserving. Thank you God Bless, do U HV networking videos? Agnelo

[@anandiyer_iitm]

Thank you for the wonderful lectures! Have a query. Given a relation, how do we know what sub-relations should we decompose into, in order to preserve dependencies? In all these examples, you had some pre-existing sub-relations and checked if they preserved dependencies? For example, given a relation with 10 attributes, whose functional dependencies are known, how to decide how should I choose the sub-relations so that I have a dependency preserved in this new design?

[@barrybarry5092]

Ma'am, I wonder how you get these sub relations directly from the original relation?

[@deepikayadav6752]

Thnq ma'am this lacture helps me to clear mt doubt.

[@elyasaf755]

@Jenny's lectures CS/IT NET&JRF is the first one not preserving, and the second one is preserving? Thank you so much for the great lectures!

[@learnit3767]

Hi Jenny mam. Why don't you make videos on solving programming questions where you can pick up questions which involve the concept ds and algo.

[@NazliHD]

YOU ARE PERFECTT 🔥❤

[@pavankalyanlingineni9516]

I have a doubt, how are you figuring out R1, R2, R3 or how can i know into how many relations that I need to divide and what would be the attributes in it.

[@Payal_Ojha]

I love your way of explanation but that Radhakrishn Locket in your neck has stolen my heart❤

[@shashwatjha9491]

Ma'am How did u write the sub relations for the given Functional dependency ? Is it always given in the question?

[@khanaurangzeb1789]

Same

[@oppertunecareer5516]

Same question mam

[@kaliprasadbabupatcha5869]

same doubt

[@samihahsharif7441]

Yes, the sub relations will be given. The real part is you have to find out if this decomposition is dependency preserving or not?

[@kalpanagupta1685]

Thanks a lot mam for every video.

[@chamarthykoushik204]

Mam you didn't tell how to divide them to sub relations so that they hold dependency preserving...can anyone please explain

[@karandhar316]

I have the same question

[@Vani-sf9tc]

seconed example is depedency presrving f1: a->b,b->a} f2:{ b->c,c->b} f3: c->d,d->c) g cover f and f cover g

[@VishalJha-p5o]

Ha toh

[@sawanverma3605]

Ty mam u r great 😊❤

[@prof.vishnupatidar4622]

Great lecture

[@deepakanuraagsathyanarayan9666]

The exercise you gave is not dependency preserving decomposition right!! F1 U F2 U F3 does not have D->A right please reply!!

[@Uniquevibers944]

Same question here

[@AamirKhan-id4uu]

I too have same question....

[@anupamguin7564]

Nice video ☺️👍

[@SHIVAMGUPTA-kl5gk]

Mam plz more videos on dbms topic ,mam upload 1or 2 videos at least in a week

[@nandhinigopinath3078]

First question not dependency preserving, 2nd question dependency preserving. Please let me know whether these answers are correct or not.

[@Vishnuteja_2812]

Correct

[@atulgupta5181]

While taking subset of C,D,E there is no check of subset EC closure why?

[@40_jaishreerana45]

Mam could you please explain how to divide relation into sub relations

[@harshgour9308]

Suppose R(ABCD) and FD:- {AB->C , BD->D} here AB is the only candidate key, will BC->D gives partial dependency ? I mean if combination of prime and non prime attribute determines Non prime attribute gives partial dependency or Not as there is a confusing example in geeksforgeeks NF2 section Example no 2, which is showing it as partial dependency...please clear my doubt

[@khushbookumari-so8dt]

R(ABCDE) FD {A->BCDE, BC->AED, D->E} .R1(AB) , R2(BC), R3(CDE) Decomposition is not dependency peserving.

[@funsefan5096]

Mam ,please make more videos on DBMS

[@pavankumarreddyg9560]

In 1st questions u solveed I took like this R1(abc) R2(cde) I am getting it's not dependency is it crt or wrong

[@AamirKhan-id4uu]

Mam in question 1: dependency preserving. 2 : not dependency preserving I got ... Please reply mam

[@sannidiashish2312]

answer : Prime Attributes = A,B,C,D,E Non Prime Attributes = NONE hence , 3NF is the highest normal form

[@gladislohar8997]

Bcnf is correct

[@farhanmujawar4005]

Is that a full dbms course...mam plz let me know....writin this wrt the above cmmnt

[@chamarthykoushik204]

Please can anyone explain how to divide into sub relations that preserve dependency preserving....and how did she exactly divide into R1(A,B) R2(B,C) R3(C,D,E) means how can we divide them

[@AmritaKumari-fj5mo]

yes maam please

[@anishjoshi1999]

Thank you mam

[@deepaksharma5831]

why not take (CE)+ closure

[@krayomatic2011]

Because C already determines both D and E, so CE will also determine both, we are not getting any new attributes

[@FINANCIALYOGI]

I tried becoming member by using debit card, unable, kindly advice.

[@-HarishkumarG]

Why trivials are discarded in dependancy preserving decomposition ?

[@chiragkap795]

Can you make videos on java netbeans??

[@rits.fitnessclub3050]

mam can u tell us the method relation or table covert into sub relation .

[@tonystack1412]

Ma'am can you please make videos on real time unix coding??

[@geogaddi84]

Couldn't you just check to see if each FD is in R1UR2UR3 directly? It seems like you're adding a lot of steps.... but maybe I am missing something

[@Uniquevibers944]

Both the problems are not dependency preserving. Referring 2nd pbm, D->A hasn't been covered up in G.

[@BCSMANJUS]

Why can't we split this relation into a, B, C and c, d, e

[@Sanai9]

1st FDs of G are:-{A->B,D->E} HENCE not PD 2nd FDs of G are:-{A->B,B->A,C->B,B->C,C->D,D->C} hence PD

[@radhikasaini9333]

1 question - not dependency preserving decomposition 2 question - dependency preserving decomposition

[@udayabhi185]

Same

[@vishnu.kshetty4378]

mam how to divide r1 and r2

[@nishathangavel6714]

Yes highest is 3 NF is it correct

[@lavitdubey561]

1st viewer 😇

[@bharat11]

Maam please upload some videos on java programming.

[@gulamgareebnawaz7638]

Algorithm kab strt krogi mam

[@JennyslecturesCSIT]

Already uploaded

[@033_saumyakumari7]

1st - Not Dependency Preserving 2nd - dependency preserving

[@RajeshYadav-tr1sr]

Ma'am aapko ek mail kiya hai..can you please check that.need some info for books

[@siddhartharaj8451]

1. not dependency preserving. 2. dependency preserving

[@Vani-sf9tc]

first one example not dependency preserving f1 : a->b f2 { }empty, f3:d->e plese conform mama

[@farmygaming9609]

1st question is not dependency preserving , and 2nd question is dependency preserving.

[@Vani-sf9tc]

please start computer organization and architecture

[@gopalprasad4447]

Right now i am in last year but if u join in my college as a teacher once i again take readmission

[@chetanraj7974]

Hii mam , would you like to have dinner ? Final year student at IIT Kanpur

[@chanabasayyasindagimath9516]

Please Release the NEW ARTICLES FOR ADVERTISEMENTS Mdm.... please

[@shivalikagupta3433]

First is not dependency preserving and second is dependency preserving.

[@40_jaishreerana45]

I will be thankful if you clear my doubt. Pls help

[@darthdaenerys]

1. Not dependency preserving 2. Dependency preserving

[@maitridharmajumder9635]

And 2 is bcnf

[@prabhavathib871]

Kindly pin the correct answers in the comment for the assignment questions

[@mdgolamrabbani507]

The first example is Not DP and The second example is DP

[@maitridharmajumder9635]

1 is not dependency preserving decomposition

[@AamirKhan-id4uu]

1. Yes. 2. No

[@Anitakumari-hx4tl]

1st is not dpd and 2nd is dpd

[@Uriah_Lysander_Netherborne]

aise

[@jayprajapati9]

First nahi hu kyoki ladies First 🥰

[@lavitdubey561]

MR.JOKER X Nikal pehli fursat m

[@saivarun1748]

1st question is not preserving and 2nd is preserving

[@jyothsnakaruparthi7011]

both satisfy the dependency preserving .. is my answer correct

[@deepaksharma5831]

anybody explain

[@KrishnaPandit1999]

1'st question: not DP 2'nd question: DP

[@vaibhavsinhbihola1]

1 is not dependecy preserving 2 is dependency preserving

[@hetjayeshbhaipatel1075]

how 2nd is dependency preserving as we are not getting any dependency of D -> A

[@sasikalav5058]

1: NOT DPD 2: DPD

[@govindchavan7689]

1st Not PD 2nd PD