FD_practice_key_part1

let R be a relation defined on the set z by aRb if a < b. What property/properties are violated? A. Symmetric & transitive B. Reflexive & Symmetric C. Reflexive & Transitive D. All three properties

Suppose RR is a relation with attributes A1,A2,…,AnA1,A2,…,An. How many superkeys will RR have if a) The only candidate key is A1A1. b) The only candidate keys are A1A2A1A2 and A1A3A1A3.

Here's a relation (R), its attributes and its functional dependencies (F): R(A, B, C, D, E, F, G) BC -> DG CD -> F FG -> A   1. compute the closure of {ACD}+ 2. compute the closure of {F}+ 3. what are the keys of R?

Give all the keys of R if the functional dependencies on R in each of the following cases

Let A1, A2, and A3 be attributes in a relation R. If both of these functional dependencies hold: A1 → A2 and A2 → A3, then A1 → A3 holds, because of the_? rule.

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Develop a program that takes as input: 1- A relation R with a set of attributes. The number of attributes should be variable. 2- A set of functional dependencies F that holds on R. The number of functional dependencies should be variable. And your program should do the following: 1- Find and print out the list of all possible candidate keys, (not the super keys), of R based on F.

Consider the Relation R4 = (A,C,B,D,E,F), with Functional Dependencies: A -> B, C -> D, E -> D. What is the Candidate Key for R4?

4. Write the relation matrix for the relation R on the set (a,b.c.d.e.f) which is defined as follows: R={a,a), (a,b), (a,c), (b,a). (b,c). (c,a), (c,b), (d,d), (f.f).

Question 3 Consider a relation A(P, Q, R, S, T) with following functional dependencies. i. P - QR ii. R- Q iii. S-T iv. T- S Infer all possible functional dependencies, superkeys and keys.

Consider a relation R with six attributes A, B, C, D, E, F. You are given the following dependencies: FD C B C-F EA-C Its candidate keys are ((E, A)). Read the following three questions carefully and choose the correct option by entering only i, ii, iii, or iv. 1. Which of the following is a non-prime attribute for the relation R?. H II. A mi. C iv. All attributes of the relation Rare non-prime attributes 2. Which of the following is a Very Good functional dependence for the relation R? LEAC RC B E-F iv C- F 3. Which of the following is the normal form of the relation R? 1. Third normal form Second normal form First normal form IV Boyce-Codd normal form IV 4

We have a relation with the following attributes: R={A,B,C,D,E} and all the attributes are atomic.   Primary key of this relation is AB. What is the normal form of this relation given the following functional dependencies:   AC→D, AB→C, AB→D, AB→E   Select one:   a. First Normal Form   b. This relation is not normal.   c. Third Normal Form   d. Second Normal Form

Correct and detailed answer. No plagarism please!

Correct and detailed answer will be Upvoted else downvoted. Thank you!

Consider the relation R(A, B, C, D, E), where it is known that the only keys are KA, C, D} and {D, E}: Give a set of functional dependencies that will make {A, C, D} and (D, E} be the only keys of R. This set should be such that if you delete any of the functional dependencies, then the keys of R will be something other than {A, C, D} and {D, E}.

QUESTION8 Here's a relation (R), its attributes, and its functional dependencies (F): R(A, B, C, D, E, F G) BC → DG CD-→F FG A 1-Compute the closure of (ACD}+ 2-Compute the closure of (F)+ 3-What are the keys of R?

Consider the following functional dependencies that hold on R(ABCDEF): AB-> CD, E -> C, B -> EF Is R in 3NF? Explain your answer in detail and decompose the relation, as necessary, into a collection of relations that are in 3NF. Make sure you first find all the key(s) of R so that you will be able to tell whether an attribute is prime.

Consider the following set F of functional dependencies on the relation schema (А, В, С, D, E, G): А— ВCD ВС — DE В — D D → A

A decomposition of a relation R into Rị and R2 is dependency preserving, if - (a) R can be reproduced by natural join of R1 and R2 (i.e, by R1 ¤R2). (b) All the functional dependencies can be checked without computing R1 ¤R2. (c) R¡NR2 forms a super key for either R1 or R2. (d) All of them.

I need quick and short answ.Without explanation

Let W(A, B) and Q(C,D) be two relation schemas. Let r₁ and r2 be the corresponding relation instances. B is a foreign key that refers to C in r2. Assuming that all tuples in r₁ and r2 satisfy referential integrity constraints, which of the following is ALWAYS TRUE? (А) Пв (г1) - Пс (rz) =Ø (B) IIc (₂)-118 (1₁) = 0 (С) Пв (г1 ) = Пс (12) (D) Пв (r1 ) - Пс (12) +Ø OB OD OA O C

DATABASE SYSTEM A relation R is given which is R(A,B,C,D,E). It has the following functional dependencies: BC  -> ADE , D -> B. Answer the following based on this information. Which normal forms does this relation satisfy? Which type of dependencies does this relation violate? Normalize the relationship so that it decomposes to 3NF.

If we have a set of attributes as R : (A, B, C, D, E, F) and functional dependencies are: AB -> C B  -> AE C  -> D What are the candidate key(s)?

Consider the relation instance and functional dependencies below. Which of these FDs hold on the instance and which do not? A BC 2 4 АВ — С A → B A → C В > с АС — В ВС — А 3 4 В > А C → A C → B 1 3 5 2 4

Consider the relation schema R(A, B, C, D, E, F) and the set S = {AB->C, BC->AD, D->E, C->B) of functional dependencies. Assuming that R is decomposed into the relation schemas R1(A,B), R2(B,C), R3(A,B,D,E) and R4(E,F). Use the Chase test to show if this is a lossless decomposition.

Consider a relation named as BOOK that contains data about the books in a library. BOOK relation was initially created with the attributes BookID (an id that library assigns), ISBN, CopyNr (used to differentiate copies of the same book), Title, PublYear, Author, and AuthorBornYear.  Primary key: BookID, CopyNr and Author Candidate key: ISBN, CopyNr and Author Below is three dependencies of attributes:    Dependency 1 (D1): ISBN, Title, PublYear, AuthorBornYear were dependent on BookID, CopyNr and Author Dependency 2 (D2): Title and PublYear were dependent on BookID, CopyNr Dependency 3 (D3): AuthorBornYear was dependent on Author .  First determine which normal form (1NF, 2NF, 3NF or BCNF) the above relation is, and why.                                                              Then, if necessary, convert the above relation to the highest normal form (BCNF). Write any assumptions that you make.