DBI202 Exam 1 Questions with 100% Correct Answers

DBI202 Exam 1 Questions with 100% Correct
Answers
Which of the following statement is belong to DML?

Select one:

a. CREATE

b. INSERT

c. GRANT

d. ALTER

b

Suppose a relation R(A,B) and S(B,C) are bags. R has 2 tuples (1,3), (2,4) and S has 3

tuples (1,2), (1,2) and (4,5). The theta join R ⋈ R.B>S.B S has __________ tuples

Select one:

a. 2

b. 3

c. 6

d. 4

d

Choose a right statement about high level design.

Select one:

a. high level design is process of constructing a model of information used in an

enterprise based on a specific data model, but independent of a particular DBMS or

other physical considerations

b. High-level design describes exactly the information needs of the business

,c. high level design is process translating the logical description of the data into

technical specifications for storing and retrieving data

b

Which of the followings is false about UML?

Select one:

a. None of the others

b. UML does not support the multi-way relationships

c. UML classes are sets of objects, with states and behaviors

d. UML supports the subclass structures

a

In __________, a key is composed of attributes, some or all of them belong to another

entity set

Select one:

a. Weak entity set

b. Sub class

c. Super class

d. Supporting entity set

a

Which of the following statements is valid?

Select one:

a. If A->->B, B->->C hold in relation R, then A->->C holds, too

b. If A->->B, B->C hold in relation R, then A->->C holds, too

c. If A->B, B->->C hold in relation R, then A->->C holds, too

d. All of the others

,d

Which of the followings is TRUE about E/R model?

Select one:

a. Attributes are associated to both entity sets and relationship types

b. Attributes cannot have the same name in the same entity set

c. Attributes are very simple types, e.g. integers or character strings

d. All of the others

d

Which of the following statements is correct about weak entity set?

Select one:

a. Weak entity set can have only one supporting relationship

b. None of the others

c. Weak entity set can not have more than one supporting entity set

d. The key of weak entity set includes all key attributes from supporting entity sets

d

What often is used to describe about data model?



Select one:

a. All of others

b. Structure of data

c. Constraints

d. Operations on data

a

, Suppose relation R(A,B,C,D,E), and set of FD's S={ A -> D, BD -> E}. Which of the

followings is a key of R?

Select one:

a. AB

b. ABC

c. ABCD

d. A

b

Suppose a relation R(A,B,C,D) and a constraint says that in every tuple of this relation

a value on D component must be equal to the total of values on other components. How

can we implement this constraint?

Select one:

a. We create a referential integrity constraint

b. We create a not null constraint

c. We create four attribute-based CHECK constraint for each attribute

d. We create a tuple-based CHECK constraint

d

Suppose there are two relations R(A,B,C) and S(E,F), and a referential integrity

constraint from attribute F of S to attribute A of R, where A is a primary key of R.

Which of the followings can violate this constraint ?

Select one:

a. All of the others

b. Insert a new tuple to the relation S