Discuss the correspondence between the e-r model construct and the relation model construct .
Answers
The first stage of information system design uses these models during the requirements analysis to describe information needs or the type of information that is to be stored in a database. In the case of the design of an information system that is based on a database, the conceptual data model is, at a later stage (usually called logical design), mapped to a logical data model, such as the relational model; this in turn is mapped to a physical model during physical design. We create a relational schema from an entity-relationship(ER) schema.
In the case of the design of an information system that is based on a database, the conceptual data model is, at a later stage (usually called logical design), mapped to a logical data model, such as the relational model; this in turn is mapped to a physical model during physical design. Sometimes, both of these phases are referred to as "physical design". Key elements of this model are entities, attributes, identifiers and relationships.