Week 6

Question 1

A high-level declarative language for specifying relational queries.

Answer 1

relational calculus

Question 2

A ____ operation operates on single relations.

Answer 2

unary

Question 3

A ___ operation operates on two tables by combining related tuples (records) based on join conditions.

Answer 3

binary

Question 4

An operation that can summarize data from tables, as well as additions types of Join and Union operations.

A. Relational operation
B. Functional operation
C. Aggregate functions

Answer 4

C. Aggregate functions

Question 5

What operation is used to choose a subset of tuples from a relation that satisfies a specific condition?

Answer 5

SELECT

Question 6

The SELECT operation is ____; it can be applied in any order.

A. strict
B. commutative
C. transitive

Answer 6

B. commutative

Question 7

What operation is used to choose columns from a table?

Answer 7

PROJECT

Question 8

The sigma (σ) symbol is used for what operation?

A. select
B. project
C. union

Answer 8

A. select

Question 9

The pi (π) symbol is used for what operation?

A. select
B. project
C. union

Answer 9

B. project

Question 10

T/F: the PROJECT operation removes duplicate tuples if the attribute list includes only nonkey attributes.

Answer 10

True

Question 11

The rho (ρ) symbol is used for what operation?

A. select
B. project
C. rename

Answer 11

C. rename

Question 12

The ___ operation is used to change the name of an intermediate operation. It is used with using the (TABLE)

Answer 12

RENAME

Question 13

In SQL, the ____ operation is used by using DISTINCT in a SELECT query.

Answer 13

PROJECT

Question 14

in SQL, AS is used as the ____ operation.

Answer 14

RENAME

Question 15

The operation that includes all tuples that are in X or Y, or in both X and Y. Duplicates are eliminated. (X ∪ Y)

A. UNION
B. INTERSECTION
C. SET DIFFERENCE

Answer 15

A. UNION

Question 16

The operation that includes only the tuples that are in both X and Y. (X ∩ Y)

A. UNION
B. INTERSECTION
C. SET DIFFERENCE

Answer 16

B. INTERSECTION

Question 17

The result of tuples that are in X but not in Y. (X - Y)

A. UNION
B. INTERSECTION
C. SET DIFFERENCE

Answer 17

C. SET DIFFERENCE

Question 18

UNION and INTERSECTION are ____ operations. Meaning the operation returns the same values whether it is X ∪ Y or Y ∪ X

Answer 18

commutative

Question 19

The _____ operation is denoted by X. It produces a new element by combining every tuple from one relation with every tuple from another relation.

Answer 19

CARTESIAN PRODUCT (CROSS PRODUCT)

Question 20

What operation is used to combine related tuples from two relations into a single longer tuple?

Answer 20

JOIN

Question 21

The ⋈ symbol is used for what operation?

Answer 21

JOIN

Question 22

A ___ JOIN requires that the two join attributes have the same name in both relations.

A. natural
B. theta
C. equi

Answer 22

A. natural

Question 23

This operation is applied to two relations where the attributes of S are a subset of the attributes of R. ( R(Z) ÷ S(X) )

Answer 23

DIVISION

Question 24

T/F: A generalized projection operation is used to compute values for a report.

Answer 24

True

Question 25

A(n) ____ is a mathematical operation applied to a collection of numeric values (SUM, AVERAGE, MAXIMUM, MINIMUM)

Answer 25

aggregate function