Relational Database Flashcards
invented the relational model for database management
Dr. E.F. Codd,
represents the database as a collection of relations, with relations pertaining to tables with rows and columns.
RELATIONAL MODEL
used extensively in mathematics to provide a framework in which an assertion (statement of fact) can be verified as either true or false.
Predicate logic
a part of mathematical science that deals with sets, or groups of things, and is used as the basis for data manipulation in the relational model.
Set theory
a type of database management system that stores information in tables- rows and columns of data.
RELATIONAL DATABASE
the rows of a table
records
the columns of a table
fields
as a two-dimensional structure composed of rows and columns
table (relation)
Each blank represents data about an entity
row (tuple)
Each table column represents an blank , and each column has a distinct name.
attribute
Each blank of a row and column represents a single data value.
intersection
All values in a column must conform to the same data format. Each column has a specific range of values known as the blank
attribute domain
serves as the unique identifier of a specific tuple in a relation
Primary key
a pool of legal values for a given attribute
Domain
a field in one table whose values are constrained to be values of the primary key in another table
Foreign key
refers to the trustworthiness of system resources over their entire life cycle
DATA INTEGRITY
four essential qualities or core attributes of data integrity
- completeness
- currency / timeliness
- accuracy / correctness
- validity / authorization
Types of Data Integrity Rules
rules that apply to a particular database
Specific Integrity Rules
rules that apply to all relational database
General Integrity Rules
Types of Integrity Constraints
states that every table must have a primary key and that the column or columns chosen to be the primary key should be unique and not null
Entity Integrity Constraint
any foreign key value can only be in one of two states the database must not contain any unmatched foreign key
Referential Integrity Constraint
a set of mathematical principles that form the basis for manipulating relational table contents.
RELATIONAL ALGEBRA
The use of relational algebra operators on existing relations (tables) produces new
relations is called blank
closure
The condition to be evaluated is also known as blank
predicate
fundamental relational operators
retrieves subset of rows
SELECT
retrieves a subset of columns
PROJECT
Merges two union-compatible tables into a new table, dropping the duplicate rows
UNION
Retrieves rows that are common to two union-compatible tables
INTERSECT
Retrieves rows from one table that are not found in another unioncompatible table
DIFFERENCE
Retrieves possible pairs of rows from two tables (Cartesian Product)
PRODUCT
Retrieves rows from two tables based on criteria
JOIN
Retrieves unique column values that are associated with all the unique values of another table’s column
DIVIDE
