PyQdeck LogoPyQdeckSubjects
Back to the 2024 paper

Module 2: Relational Query Languages & Design

20247m

Consider the relation R (P, Q, S, T, X, Y, Z, W) with the following functional dependencies.
PQ → X; P → YX; Q → Y; Y → ZW
Consider the decomposition of the relation R into the constituent relations according to the following two decomposition schemes.
D1 : R = [(P, Q, S, T); (P, T, X); (Q, Y); (Y, Z, W)]
D2 : R = [(P, Q, S); (T, X); (Q, Y); (Y, Z, W)]
Identify whether it is a lossless or lossy decomposition and justify your answer.

Search GoogleAsk AI

Similar questions

Database Management SystemSuppose relation R(A,B,C) is decomposed into: R1(A,B) and R2(B,C). The decomposition is lossless if: (i) B \rightarrow A or B \rightarrow C (ii) A \rightarrow B (iii) A \rightarrow C (iv) C \rightarrow B20252mDatabase Management SystemWhen is the decomposition of relation schema R into two relation schemes X and Y, said to be a loss-less-join decomposition? Why is this property so important? Explain with example.20227mDatabase Management SystemWrite a short note on: Dependency Preservation and Lossless Decomposition20257mDatabase Management SystemConsider the relation scheme R = {E, F, G, H, I, J, K, L, M, N} and the set of functional dependencies {{E, F} → {G}, {F} → {I, J}, {E, H} → {K, L}, K → {M}, L → {N}} on R. What is the key for R? (i) {E, F} (ii) {E, F, H} (iii) {E, F, H, K, L} (iv) {E}20192m
PreviousWhich of the following is true about object-oriented databases? (i) They use tables only (ii) They allow encapsulation (iii) No support for complex data (iv) Only support numeric dataNextEmployee (ename, street, city) Worksfor (ename, company_name, salary) Company (Company_name, city) Construct the SQL statements for the following (i) Create the above given tables with suitable data types and size. (ii) Find the name of employees who live in the same city where they work. (iii) Find the name of employees who have salary more than Rs. 50000. (iv) Find the name of employees who don't work in "tcs" company. (v) Find all employees whose name has second letter 'A'. (vi) Find the employee's name having second highest salary.