Databases & Relational Theory Flashcards

Question 1

Relational Algebra: Full Outer Join (Symbol)

Accepted Answer

$r \fullouterjoin s$

Question 2

DBMS

Accepted Answer

Database Management System; software that interacts with end users, applications, and the database itself to capture and analyze data.

Question 3

Data Independence

Accepted Answer

The ability to modify a schema definition in one level without affecting a schema definition in the next higher level.

Question 4

Logical Data Independence

Accepted Answer

The ability to change the logical schema without changing the external schema or user views.

Question 5

Physical Data Independence

Accepted Answer

The ability to change the physical schema without changing the logical schema.

Question 6

DDL (Data Definition Language)

Accepted Answer

SQL commands used to define or modify database structure (e.g., CREATE, ALTER, DROP).

Question 7

DML (Data Manipulation Language)

Accepted Answer

SQL commands used to manage data within schema objects (e.g., SELECT, INSERT, UPDATE, DELETE).

Question 8

DCL (Data Control Language)

Accepted Answer

SQL commands used to control access to data (e.g., GRANT, REVOKE).

Question 9

TCL (Transaction Control Language)

Accepted Answer

SQL commands used to manage the changes made by DML statements (e.g., COMMIT, ROLLBACK).

Question 10

Superkey

Accepted Answer

A set of one or more attributes that can uniquely identify a tuple (row) in a relation.

Question 11

Candidate Key

Accepted Answer

A minimal superkey; a superkey with no redundant attributes.

Question 12

Primary Key

Accepted Answer

A candidate key chosen by the database designer as the principal means of identifying entities within an entity set.

Question 13

Foreign Key

Accepted Answer

An attribute or set of attributes in one relation that refers to the primary key of another relation.

Question 14

Entity Integrity Constraint

Accepted Answer

No primary key value can be NULL.

Question 15

Referential Integrity Constraint

Accepted Answer

If a foreign key exists in a relation, either the foreign key value must match a candidate key value of some tuple in its home relation or the foreign key value must be wholly NULL.

Question 16

Relational Algebra: Selection (Symbol)

Accepted Answer

$\sigma_{p}(r)$ (Selects tuples that satisfy predicate $p$)

Question 17

Relational Algebra: Projection (Symbol)

Accepted Answer

$\pi_{A_1, A_2, \dots}(r)$ (Selects specific columns/attributes)

Question 18

Relational Algebra: Natural Join (Symbol)

Accepted Answer

$r \bowtie s$

Question 19

Relational Algebra: Cartesian Product (Symbol)

Accepted Answer

$r 	imes s$

Question 20

Relational Algebra: Set Union (Symbol)

Accepted Answer

$r \cup s$

Question 21

Relational Algebra: Set Intersection (Symbol)

Accepted Answer

$r \cap s$

Question 22

Relational Algebra: Set Difference (Symbol)

Accepted Answer

$r - s$

Question 23

Relational Algebra: Rename (Symbol)

Accepted Answer

$\rho_{x}(r)$ (Renames relation $r$ to $x$)

Question 24

Relational Algebra: Left Outer Join (Symbol)

Accepted Answer

$r \leftouterjoin s$

Question 25

Relational Algebra: Right Outer Join (Symbol)

Accepted Answer

$r \rightouterjoin s$

Databases & Relational Theory

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