CSCI 4402: Database Systems - Module 2/Quiz 2

Suppose we want to list all students ids and names, but do not care about their addresses. Which of the following operations allows us to produce this relation?

a. Union

b. Set difference

c. Cross Product

d. Project

Project

Which of the following operations that is equivalent to combine certain selections and a cross product?

a. Intersection operation

b. Union operation

c. Join operation

d. Division operation

Join operation

Which of the following are the binary operations?

a. Rename, union, and set difference

b. Set difference, union, and project

c. Cartesian product, union, and set difference

d. Cartesian product, set difference, and project

Cartesian product, union, and set difference

If we have two relation R and S that are union compatible, the number of tuples in the output of their union equal __________

a. Number of the common tuples between R and S

b. Number of tuples in R +Number of tuples in S - Number of the common tuples between R and S

c. Number of tuples in R +Number of tuples in S

d. Could not be determined

b. Number of tuples in R +Number of tuples in S - Number of the common tuples between R and S

Which of the following relational algebra expression do?

σsalary>1200Employee

a. Finds all the salaries in Employee where the number of values is greater than 1200

b. Finds the tuples in Employee where the salary is greater than 12000

c. Finds all the tuples in Employee

d. Finds all the tuples in Employee where the salary is greater than 1200

Finds all the tuples in Employee where the salary is greater than 1200

In relational algebra, the term relation is equivalent to ________

a. Column

b. Attribute

c. Row

d. Table

Table

The select, project, and rename operations are called________

a. Unary operations

b. Binary operations

c. Ternary operations

d. None of them

Unary operations

What does the following relational operation perform?

ρA1,A2,A3,...R

a. It rename the table R

b. It returns the results of table R renaming the attributes A1,A2,A3,...

c. It returns the results of table R with the previous attribute names

d. None of the mentioned

b. It returns the results of table R renaming the attributes A1,A2,A3,...

In relational algebra, the term tuple is equivalent to ______

a. Row

b. Table

c. Attribute

d. Column

Row

The binary operation union, denoted as in the set theory by ___________

a. σ

b. ∩

c. π

d. ∪

∪

The output table schema always match the input table schema when we use the __________ operation

a. Select

b. Cross product

c. Project

d. Join

Select

The select operation selects tuples that satisfy a given predicate. We use the lower case __________ to denote selection

a. Greek letter pi (π)

b. Greek letter sigma (σ)

c. Greek letter rho (ρ)

d. Greek letter sigma (ρ)

Greek letter sigma (σ)

The project operation selects tuples with some attributes that we wish to include but some attributes we do not want to include in the final relation. We use the lowercase ______ to denote project operation.

a. Greek letter sigma (σ)

b. Greek letter pi (π)

c. Greek letter rho (ρ)

d. Greek letter sigma (ρ)

Greek letter pi (π)

Which of the following operations allows us to find the tuples that are in one relation but are not in another relation?

a. Set difference

b. Set intersection

c. Union

d. Cross product

Set difference

The expression R∩S is equivalent the expression ______________

a. (R∪S)−R

b. (R∪S)−S

c. R−(R−S)

d. R−(R∪S)

R−(R−S)

Which of the following is not a relational algebra operation?

a. Union

b. Project

c. Select

d. Manipulate

Manipulate