the process of degining a database so that it faithfully represents all aspects of the organization, including its interactions with the external environment.
a graphical technique for protraying a data base schema by showing the various entities being modeled and the important relationships among them.
anything about which the organization wants to collect and store information
REA Data Model
developed specifically for the use in designing AIS, and focuses on the business semantics underlying an organization's value chain activities. It provides guidance for database design by identifying what entities should be included in the AIS database and by prescibing how to structure relationships among the entities in the database.
something that has economic value in an organization
various business activities about which management wants to collect information for planning or control purposes.
people and organizations that participate in events about whom information is desired for planning, control, and evaluation.
these describe the nature of the relationships between two enetities by indicating how many instances of one entity can be linked to each specific instance of another entity.
cardinality that can either be zero or one, depending upon whether the relationship between the two entities is optional or mandatory.
cardinality that can either be one or many, depending upon whether each instance of entity A can be linked to at most one instance or potentially many instances of entity B.
one to one relationship
exists when the maximum cardinality for each entity in the relationship in 1.
one to many relationship
exists when the maximum cardinality of one entiry in the relationship is 1 and the maximum cardinality for the other entity in that relationship is many.
many to many relationship
exists when the maximum cardinality for both entities in the relationship is many.