SIf a decomposition of a relation R into R¡ and R2 is lossless, then which of the followings are true? |(a) R can be reproduced by natural join of R1 and R2 (i.e, by R¡ ¤R2).. |(b) All the functional dependencies can be checked without computing Rị ¤ R2. (c) R1NR2 forms a super key for either R1 or R2. |(d) All of them.

SIf a decomposition of a relation R into R¡ and R2 is lossless, then which of the followings are true? |(a) R can be reproduced by natural join of R1 and R2 (i.e, by R¡ ¤R2).. |(b) All the functional dependencies can be checked without computing Rị ¤ R2. (c) R1NR2 forms a super key for either R1 or R2. |(d) All of them.

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

See similar textbooks

Similar questions

Let's suppose, a relation R=(A, B, C, D, E. H) with a set of functional dependencies F: (AE->BC, B ->AD, CD->E, E→CD, A->E) is given. Relation R (A, B, C, D, E, H) is decomposed into R1 (A, B, C, D) and R2 (A, B, E, H). Find out whether the decomposition is lossless or not, and whether it is dependency preserving or not.
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.
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
Consider the relation R = {A, B, C, D, E, F, G, H, I,J} and the set of functional dependencies F = { {A, B} → {C}, {A} → {D, E}, {B} → {F}, {F} →{G, H}, {D} → {I, J} }. (b) Whether (A,B,F} is a super key? Whether {A,B,F} is a candidate key? Why? (c) Whether {A,D} is a super key? Whether {A,D} is a candidate key? Why?
23 of 40 Let R(A, B, C, D, E, F) be a relation with FD's: {D → CE, C → BDE, E → AD, AF → E, B → DF}. Which of the following statements is correct? Select one: O Ris in BCNF but not in 3NF. O Ris in 3NF but not in BCNF. O Ris not in 3NF and not in BCNF. O R is in 3NF and in BCNF.
For each of the following pairs of expressions, give instances of relations thatshow the expressions are not equivalent. ΠA(r − s) and ΠA(r) − ΠA(s).
What is the highest normal form for the following relation and its functional dependencies? Assume it is in INF. A(x, w. z) • X- w 1NF BCNF 2NF 3NF cannot be determined
Solve the following:
3. Consider a relation R from X={1,2,3,4} to Y={a,b,c,d). R= {(1,b), (2,c), (2,d), (3,c), (4,a) } Please draw the relational matrix of R.
sub: ML
Subject:Database
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