is called specialization and generalization.
ENHANCED ENTITY RELATIONSHIP OR EXTENDED ENTITY RELATIONSHIP
In software engineering, an Entity - Relationship model(ER model for short) is an abstract and conceptual representation of data. Entity-relationship modeling is a database modeling method, used to produce a type of conceptual schema or semantic data model of a system, often a relational database, and its requirements in a top-down fashion. Diagrams created by this process are called entity-relationship diagrams or ER diagrams.learn more www.ngprakasam.hpage.com
entity relation model for hospital database
yes
Entity-Relationship diagrams are useful for modelling data and the relationships between the data. They can be used when the constraints between data are relatively simple. They do not allow specification of interactions between the data or model how the data changes (there are no processes in Entity-Relationship). Entity-Relationship diagrams are most often used to model databases.
Entity-relationship model advantages and disadvantages AdvantagesDisadvantagesConceptual simplicityVisual representationEffective communicationIntegration with the relational database modelLimited constraint representationLimited relationship representationNo representation of data manipulationLoss of information
mandatory and optional
AdvantagesConceptual simplicityVisual representationEffective communicationIntegration with the relational database model
draw an er diagram on attendance management system
er daigram and dfd retaurent management?
An entity-relationship diagram for online banking includes the process of online banking and the relationship between each step. It is a model that maps out, describes, and defines how components are linked for online banking.
Martin Gogolla has written: 'An extended entity-relationship model' -- subject(s): Entity-relationship modeling, Prolog (Computer program language), SQL (Computer program language)