 A directory of Objective Type Questions covering all the Computer Science subjects. Here you can access and discuss Multiple choice questions and answers for various compitative exams and interviews.

 61. R(A,B,C,D) is a relation. Which of the following does not have a lossless join, dependency preserving BCNF decomposition? a. A->B, B->CD b. A->B, B->C, C->D c. AB->C, C->AD d. A ->BCD

 62. Consider a relation geq which represents “greater than or equal to”, that is, (x,y) ∈ geq only if y >= x. create table geq ( ib integer not null ub integer not null primary key 1b foreign key (ub) references geq on delete cascade ) Which of the following is possible if a tuple (x,y) is deleted? a. A tuple (z,w) with z > y is deleted b. A tuple (z,w) with z > x is deleted c. A tuple (z,w) with w < x is deleted d. The deletion of (x,y) is prohibited

 63. Given the following relation instance. x y z 1 4 2 1 5 3 1 6 3 3 2 2 Which of the following functional dependencies are satisfied by the instance? (GATE CS 2000) a. XY -> Z and Z -> Y b. YZ -> X and Y -> Z c. YZ -> X and X -> Z d. XZ -> Y and Y -> X

 64. Consider the relation X(P, Q, R, S, T, U) with the following set of functional dependencies F = { {P, R} → {S,T}, {P, S, U} → {Q, R} } Which of the following is the trivial functional dependency in F+ is closure of F? a. {P,R}→{S,T} b. {P,R}→{R,T} c. {P,S}→{S} d. {P,S,U}→{Q}

 65. A relational database contains two tables student and department in which student table has columns roll_no, name and dept_id and department table has columns dept_id and dept_name. The following insert statements were executed successfully to populate the empty tables: Insert into department values (1, 'Mathematics') Insert into department values (2, 'Physics') Insert into student values (l, 'Navin', 1) Insert into student values (2, 'Mukesh', 2) Insert into student values (3, 'Gita', 1) How many rows and columns will be retrieved by the following SQL statement? Select * from student, department a. 0 row and 4 columns b. 3 rows and 4 columns c. 3 rows and 5 columns d. 6 rows and 5 columns

 66. A table has fields Fl, F2, F3, F4, F5 with the following functional dependencies   F1 → F3   F2→ F4   (F1 . F2) → F5 In terms of Normalization, this table is in a. 1 NF b. 2 NF c. 3 NF d. none of the above

 67. Which of the following is NOT a superkey in a relational schema with attributes V, W, X, Y, Z and primary key V Y ? a. V X Y Z b. V W X Z c. V W X Y d. V W X Y Z