Relational Schema
Q21.
Which of the following is NOT a superkey in a relational schema with attributes V,W, X, Y, Z and primary key V Y?Q24.
Let x, y, z, a, b, c be the attributes of an entity set E. If {x}, {x,y}, {a,b}, {a,b,c}, {x,y,z} are superkeys then which of the following are the candidate keys?Q25.
Consider the relation scheme R = (E, F, G, H, I, J, K, L, M, N) and the set of functional dependencies {{E,F}\rightarrow{G}, {F}\rightarrow{I,J}, {E,H}\rightarrow{K,L}, {K}\rightarrow{M}, {L}\rightarrow{N} } on R. What is the key for R?Q26.
Consider a relational table with a single record for each registered student with the following attributes. 1. Registration_Number: Unique registration number for each registered student 2. UID: Unique Identity number, unique at the national level for each citizen 3. BankAccount_Number: Unique account number at the bank. A student can have multiple accounts or joint accounts. This attributes stores the primary account number 4. Name: Name of the Student 5. Hostel_Room: Room number of the hostel Which of the following options is INCORRECT?Q27.
The maximum number of super keys for the relation schema R (E, F, G, H) with E as the key is __________.Q28.
Given an instance of the STUDENTS relation as shown below For (StudentName, StudentAge) to be a key for this instance, the value x should NOT be equal to_______.Q29.
The following functional dependencies are given: AB\rightarrow CD,AF\rightarrow D,DE\rightarrow F,C\rightarrow G,F\rightarrow E,G\rightarrow A Which one of the following options is false?Q30.
Consider a relation scheme R=(A,B,C,D,E,H) on which the following functional dependencies hold: {A\rightarrowB, BC\rightarrowD, E\rightarrowC, D\rightarrowA}. What are the candidate keys of R?