Data Modelling

Key Terms

conceptual model: the logical structure of the entire database

conceptual schema: another term for logical schema

data independence: the immunity of user applications to changes made in the definition and organization of data

data model: a collection of concepts or notations for describing data, data relationships, data semantics and data constraints

data modelling: the first step in the process of database design

database logical design: defines a database in a data model of a specific database management system

database physical design: defines the internal database storage structure, file organization or indexing techniques

entity relationship diagram (ERD): a data model describing the database showing tables, attributes and relationships

external model: represents the user's view of the database

external schema: user view

internal model: a representation of the database as seen by the DBMS

logical data independence: the ability to change the logical schema without changing the external schema

logical design: where you create all the tables, constraints, keys, rules, etc.

logical schema: a conceptual design of the database done on paper or a whiteboard, much like architectural drawings for a house

operating system (OS): manages the physical level of the physical model

physical data independence: the immunity of the internal model to changes in the physical model

physical model: the physical representation of the database

schema: an overall description of a database