THE RELATIONAL DATABASE MODEL

relational data model

changed all of that by allowing the designer to focus on the logical representation of the data and its relationships, rather than on the physical storage details

logically, physically

relational model enables you to view data______rather than ______

E. F. Codd

The relational model, introduced by ____________ in 1970, is based on predicate logic and set theory.

predicate logic, set theory

The relational model, introduced by E. F. Codd in 1970, is based on __________ and _______

predicate logic

used extensively in mathematics, provides a framework in which an assertion (statement of fact) can be verified as either true or false.

set theory

is a mathematical science that deals with sets, or groups of things, and is used as the basis for data manipulation in the relational model.

table

A _________ is perceived as a two-dimensional structure composed of rows (tuple) and columns.

relation

A table is also called a ________ because the relational model’s creator, E. F. Codd, used the two terms as synonyms.

persistent

You can think of a table as a __________representation of a logical relation—that is, a relation whose contents can be permanently saved for future use.

entity set

a group of related entity occurrences

entity set

For example, a STUDENT table contains a collection of entity occurrences, each representing a student

What are the characteristics of a relational table

1. A table is perceived as a two dimensional structure composed of rows and columns

2. Each table row (tuple) represents a single entity occurrence within the entity set.

3. Each table column represents an attribute, and each column has a distinct name.

4. Each intersection of a row and column represents a single data value.

5. All value in a column must conform