Correspondence between ER and
Relational Models
|
ER MODEL |
RELATIONAL MODEL |
|
Entity Type |
“Entity” relation |
|
1:1 or 1:N relationship type |
Foreign key |
|
M:N relationship type |
“Relationship” relation and 2 FKs |
|
Simple attribute |
Attribute |
|
Composite attribute |
Set of simple component attributes |
|
Multi-valued attribute |
Relation and foreign key |
|
Key attribute |
Primary (or Secondary) key. |
In the process of mapping the ER Model to the
Relational Model, multi-valued attributes, composite attributes, or the
combination of both get converted into a separate relation. The relations that
have attributes also get mapped to a separate relation (table).
After mapping the ER Model to the Relational Model, the following relational models were obtained.
