Database Design(Normal Forms)

Question 51

An attribute A of datatype varchar (20) has value ‘Ram’ and the attribute B of datatype char (20) has value ‘Sita’ in oracle. The attribute A has _______ memory spaces and B has _______ memory spaces.

• 20,20
• 3,20
• 3,4
• 20,4

Question 52

Consider a schema R(MNPQ) and functional dependencies M → N, P → Q. Then the decomposition of R into R₁ (MN) and R₂(PQ) is________.

• Dependency preserving but not lossless join
• Dependency preserving and lossless join
• Lossless join but not dependency preserving
• Neither dependency preserving nor lossless join.

Question 53

For a database relation R(A, B, C, D) where the domains of A, B, C and D include only atomic values, only the following functional dependencies and those that can be inferred from them are : A → C B → D The relation R is in _______.

• First normal form but not in second normal form.
• Both in first normal form as well as in second normal form.
• Second normal form but not in third normal form.
• Both in second normal form as well as in third normal form.

Question 54

Let R = (A, B, C, D, E, F) be a relation schema with the following dependencies C->F, E->A, EC->D, A->B. Which of the following is a key of R?

• CD
• EC
• AE
• AC

Question 55

DBMS provides the facility of accessing data from a database through

• DDL
• DML
• DBA
• Schema

Question 56

Consider a database table R with attributes A and B. Which of the following SQL queries is illegal ?

• SELECT A FROM R;
• SELECT A, COUNT(*) FROM R;
• SELECT A, COUNT(*) FROM R GROUP BY A;
• SELECT A, B, COUNT(*) FROM R GROUP BY A, B;

Question 57

Consider the schema R(A, B, C, D) and the functional dependencies A->B and C->D. If the decomposition is made as R1(A,B) and R2(C,D), then which of the following is TRUE?

• Preserves dependency but cannot perform lossless join
• Preserves dependency and performs lossless join
• Does not perform dependency and cannot perform lossless join
• Does not preserve dependency but perform lossless join

Question 58

Which of the following statements is/are True regarding some advantages that an object-oriented DBMS (OODBMS) offers over a relational database ? I. An OODBMS avoids the “impedance mismatch” problem. II. An OODBMS avoids the “phantom” problem. III. An OODBMS provides higher performance concurrency control than most relational databases. IV. An OODBMS provides faster access to individual data objects once they have been read from disk.

• II and III only
• I and IV only
• I, II, and III only
• I, III and IV only

Question 59

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?

• {x,y} and {a,b}
• {x} and {a,b}
• {x,y,z} and {a,b,c}
• {z} and {c}

Question 60

Which one of the following pairs is correctly matched in the context of database design?

• (1)
• (2)
• (3)
• (4)