ER model is a logical representation of an enterprise data.
ER model is a diagrammatic representation of logical structure of database.
ER model describes relationship among entities and attributes.
ER diagram is firstly developed by Peter Chen in 1976.
Advantages of ER
Model
Conceptually it is very simple: ER model is very simple
because if we know relationship between entities and attributes, then we can easily
draw an ER diagram.
Better visual representation: ER model is a diagrammatic
representation of any logical structure of database. By seeing ER diagram, we can
easily understand relationship among entities and relationship.
Effective communication tool: It is an effective communication
tool for database designer.
Highly integrated with relational model: ER model can be
easily converted into relational model by simply converting ER model into
tables.
Easy conversion to any data model: ER model can be easily
converted into another data model like hierarchical data model, network data
model and so on.
Disadvantages of ER
Model
Limited constraints and specification
Loss of information
content: Some information be lost or hidden in ER model
Limited relationship representation: ER model represents limited
relationship as compared to another data models like relational model etc.
No representation of data manipulation: It is difficult to
show data manipulation in ER model.
Popular for high level design: ER model is very popular
for designing high level design
No industry standard for notation
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