Q. Consider the following relational schema:

Suppliers(sid:integer, sname:string, city:string, street:string)
Parts(pid:integer, pname:string, color:string)
Catalog(sid:integer, pid:integer, cost:real)
(sid,pid are primary keys)
Assume that, in the suppliers relation above, each supplier and each street within a city has a unique name, and (sname, city) forms a candidate key. No other functional dependencies are implied other than those implied by primary and candidate keys. Which one of the following is TRUE about the above schema?

View solution

Q. 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 --> Catalog_no
II. Catalog_no --> Title, Author, Publisher, Year
III. Publisher Title Year --> Price

Assume {Author, Title} is the key for both schemes. Which of the following statements is true?

View solution

Q. Consider the relation scheme R = {E, F, G, H, I, J, K, L, M, M} 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?

View solution

Q. Given the following two statements:

S1: Every table with two single-valued
attributes is in 1NF, 2NF, 3NF and BCNF.

S2: AB->C, D->E, E->C is a minimal cover for
the set of functional dependencies
AB->C, D->E, AB->E, E->C.

Which one of the following is CORRECT?

View solution

Q. The maximum number of superkeys for the relation schema R(E,F,G,H) with E as the key is

View solution

Q. Which one of the following statements about normal forms is FALSE?

View solution

Q. Let r be a relation instance with schema R = (A, B, C, D). We define r1 = ΠA, B, C (r) and r2 = ΠA.D (r). Let s = r1 * r2 where * denotes natural join. Given that the decomposition of r into r1 and r2 is lossy, which one of the following is TRUE?

View solution

Q. Consider a relation scheme R = (A, B, C, D, E, H) on which the following functional dependencies hold: {A–>B, BC–>D, E–>C, D–>A}. What are the candidate keys of R?

View solution

Q. The relation scheme Student Performance (name, courseNo, rollNo, grade) has the following functional dependencies:
name, courseNo → grade
rollNo, courseNo → grade
name → rollNo
rollNo → name
The highest normal form of this relation scheme is

View solution

Q. Consider the following functional dependencies in a database:

Data_of_Birth → Age
Age → Eligibility
Name → Roll_number
Roll_number → Name
Course_number → Course_name
Course_number → Instructor
(Roll_number, Course_number) → Grade

The relation (Roll_number, Name, Date_of_birth, Age) is:

View solution

Q. 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 relations is.

View solution

Q. With regard to the expressive power of the formal relational query languages, which of the following statements is true?

View solution

Q. Relation R is decomposed using a set of functional dependencies, F and relation S is decomposed using another set of functional dependencies G. One decomposition is definitely BCNF, the other is definitely 3NF, but it is not known which is which. To make a guaranteed identification, which one of the following tests should be used on the decompositions? (Assume that the closures of F and G are available).

View solution

Q. From the following instance of a relation scheme R (A, B, C), we can conclude that :
A B C
1 1 1
1 1 0
2 3 2
2 3 2

View solution

Q. Consider a schema R(A,B,C,D) and functional dependencies A->B and C->D. Then the decomposition of R into R1(AB) and R2(CD) is

View solution

Q. Suppose the adjacency relation of vertices in a graph is represented in a table Adj(X,Y). Which of the following queries cannot be expressed by a relational algebra expression of constant length?

View solution

Q. R(A,B,C,D) is a relation. Which of the following does not have a lossless join, dependency preserving BCNF decomposition?

View solution

Q. 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?

View solution

Q. 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)

View solution

Q. 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?

View solution