Question
1. Consider a relation R(A, B, C, D, E) with the following set of functional dependencies: F = {AB -> D, AC -> E, BC
1. Consider a relation R(A, B, C, D, E) with the following set of functional dependencies: F = {AB -> D, AC -> E, BC -> D, D -> A, E -> B}. Furthermore, R is decomposed into relation S(A, B, C) and other relations.
[a] Find all functional dependencies that hold in S.
[b] Determine all possible keys for S.
[c] Determine whether S is in BCNF and/or 3NF. Explain your answer.
2. Consider the relational schema R(City, Street, Zipcode), where a tuple (C, S, Z) is in R if and only if C has a building with street address at zip code Z in that city. Further, it is assumed that the nontrivial functional dependencies in R are:
F = {CS -> Z, Z -> C}.
[a] Determine all possible keys for R.
[b] Determine all possible S BCNF and 3NF violations.
[c] Decompose R as necessary into collection of relations that are in BCNF.
[d] If we decompose R as in [c], can the original relation be always recovered exactly by joining the tuples of the new ewlations in all possible ways? If not, explain why, giving an example to illustrate your answer
Step by Step Solution
There are 3 Steps involved in it
Step: 1
Get Instant Access to Expert-Tailored Solutions
See step-by-step solutions with expert insights and AI powered tools for academic success
Step: 2
Step: 3
Ace Your Homework with AI
Get the answers you need in no time with our AI-driven, step-by-step assistance
Get Started