Database Management System
Q61.
Relation R with an associated set of functional dependencies, F , is decomposed into BCNF. The redundancy (arising out of functional dependencies) in the resulting set of relations is.Q62.
R,(A,B,C,D) is a relation. Which of the following does not have a lossless join, dependency preserving BCNF decomposition ?Q63.
Choose the correct alternatives (More than one may be correct).Indicate which of the following statements are true: A relational database which is in 3NF may still have undesirable data redundancy because there may exist:Q64.
For a database relation R(a, b, c, d), where the domains a, b, c, d include only atomic values, only the following functional dependencies and those that can be inferred from them hold a \rightarrow c b \rightarrow d This relation isQ66.
The following relation records the age of 500 employees of a company, where empNo ( indicating the employee number) is the key: empAge(\underline{empNo},age) Consider the following relational algebra expression: \Pi_{empNo}(empAge \Join_{(age > age1)} \rho_{empNo1,age1}(empAge)) What does the above expression generate?Q67.
Consider the relations r(A, B) and s(B, C), where s.B is a primary key and r.B is a foreign key referencing s.B. Consider the query Q:r \Join (\sigma _{B\lt 5}(s)) Let LOJ denote the natural left outer-join operation. Assume that r and s contain no null values. Which one of the following queries is NOT equivalent to Q?Q68.
Consider the following relation P(X, Y, Z), Q(X, Y, T) and R(Y, V): How many tuples will be returned by the following relational algebra query? Answer:______Q69.
Consider the following three relations in a relational database.Employee(eId, Name), Brand (bId, bName), Own(eId ,bId)Which of the following relational algebra expressions return the set of eIds who own all the brands?MSQQ70.
What is the optimized version of the relation algebra expression \pi _{A1}(\pi _{A2}(\sigma _{F1}(\sigma_{F2}(r)))) , where A1, A2 are sets of attributes in r with A_{1}\subset A_{2} and F1, F2 are Boolean expressions based on the attributes in r?