Database Systems Design, Implementation, and Management 11e – Ch2 – Data Models

data modeling
the first step in designing a database, the process of creating a specific data model for a determined problem domain; an iterative, progressive process
problem domain
a clearly defined area within the real-world environment, with a well-defined scope and boundaries that will be systematically addressed
data model
a relatively simple representation, usually graphical of more complex real-world data structures; main function is to help you understand the complexities of the real-world environment; an abstraction
model
an abstraction of a more complex real-world object or event
implementation-ready data model contains
a description of the data structure that will store the end-user data; a set of enforceable rules to guarantee the integrity of the data; a data manipulation methodology to support the real-world data transformations
entity
person, place, thing, or event about which data will be collected and stored
attribute
characteristic of a entity
relationship
describes an association among entities
one-to-many (1:M or 1..*) relationship
entity capitalized as a convention, so they are easily identified; one entity relating to more than one entity in the other table
Many-to-many (M:N or *..*) relationship
an entity in one table may relate to many entities in the other table while each of those entities may relate to many entities in the first table
One-to-one (1:1 or 1..1) relationship
an entity in one table may relate to one and only one entity in the other table
constraint
a restriction placed on the data; usually expressed in the form of rules
business rule
a brief, precise, and unambiguous description of a policy, procedure, or principle within a specific organization; must be rendered in writing and updated to reflect any change in the organization’s operational environment; must be easy to understand and widely disseminated to ensure that every person in the organization shares a common interpretation of the rules; set the stage for the proper identification of entities, attributes, relationships, and constraints (nouns are entities and verbs are relationships)

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