Database Management System
Q41.
Let R (A, B, C, D) be a relational schema in which the following functional dependencies are known to hold: A \to B, \; B \to C, \; C \to D and D \to B. The decomposition of R into (A,B), (B,C), (B,D)Q42.
Consider the following relational schemes for a library database: Book (Title, Author, Catalog_ no, Publisher, Year, Price) Collection (Title,Author, Catalog_ no) with in the following functional dependencies: I. Title Author \rightarrow Catalog_no II. Catalog_no \rightarrow Title Author Publisher Year III. Publisher Title Year \rightarrow Price Assume {Author, Title} is the key for both schemes. Which of the following statements is true?Q43.
Relation R has eight attributes ABCDEFGH. Fields of R contain only atomic values. F=\{CH\rightarrow G, A\rightarrow BC,B\rightarrow CFH,E\rightarrow A,F\rightarrow EG\} is a set of functional dependencies (FDs) so that F^{+} is exactly the set of FDs that hold for R. The relation R isQ48.
Consider the following implications relating to functional and multivalued dependencies given below, which may or may not be correct. i. if A \rightarrow \rightarrow B and A \rightarrow \rightarrow C then A \rightarrow BC ii. if A \rightarrow B and A \rightarrow C then A \rightarrow \rightarrow BC iii. if A \rightarrow \rightarrow BC and A \rightarrow B then A \rightarrow C iv. if A \rightarrow BC and A \rightarrow B then A \rightarrow \rightarrow C Exactly how many of the above implications are valid?Q49.
Consider a relation R with five attributes V, W, X, Y, and Z. The following functional dependencies hold: VY \rightarrow W, WX \rightarrow Z, \text{and }ZY \rightarrow V. Which of the following is a candidate key for R?